Anticipating Space Needs in Juvenile Detention and Correctional Facilities

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					U.S. Department of Justice
Office of Justice Programs
Office of Juvenile Justice and Delinquency Prevention




                                                                                                                        March 2001




Anticipating Space Needs
                                                                                                 A Message From OJJDP
in Juvenile Detention and                                                                        One of the most difficult challenges
                                                                                                 facing State and local juvenile justice
Correctional Facilities                                                                          systems is anticipating space needs
                                                                                                 in detention and correctional facilities.
                                                                                                 Underestimating future demands can
Jeffrey Butts and William Adams                                                                  lead to overcrowded and less safe
                                                                                                 facilities. Overestimating future
At some point, every facility administra-         answers are appreciated because they al-       demands can lead to mismanaged
tor in the juvenile detention and correc-         low policymakers to proceed with budget-       tax dollars and even misuse of the
tions system will be called upon to an-           ing and construction plans. Repeated expe-     extra space, such as detaining
swer the same question: How many beds             rience with estimating future space needs,     juveniles who would not otherwise be
do we need? In other words, how much              however, has taught policymakers and           confined. In either case, the cost of
space will be needed to accommodate the           practitioners alike that there are no simple   miscalculating the need for additional
number of juvenile offenders expected to          answers or, more accurately, that there are    space in secure juvenile facilities can
be placed in residential facilities in the        no simple and reliable answers. Statistical    be considerable.
future? The question may refer to a single        prediction models are only as good as the
                                                                                                 This Bulletin provides policymakers
local jurisdiction or to an entire State. It      data elements that go into them and the
                                                                                                 with information that will help them to
also may apply to the next budget period          assumptions on which they are built. Ev-
                                                                                                 determine the appropriate space
or to the next 10 years.                          ery juvenile justice administrator eventu-
                                                                                                 needed to accommodate the number
                                                  ally learns that the actual demand for de-
Policymakers ask questions about space                                                           of juvenile offenders expected to be
                                                  tention and corrections space has a way of
needs for various reasons. Demographic            proving statistical models wrong. Within a     placed in residential facilities. An
trends may indicate that a jurisdiction                                                          overview of juvenile justice system
                                                  few years, policymakers will likely return
will soon have a larger population of ju-         to ask the same question: How many beds        policies and decisionmaking that
veniles. Juvenile crimes may be occur-                                                           affect the process of assessing future
                                                  do we need?
ring more frequently or less frequently,                                                         space needs is provided, and an
and the crimes themselves may be be-              This Bulletin provides policymakers with       analysis of the different projection
coming more severe or less severe. A              information to help them answer this           models is included.
jurisdiction may be facing a financial cri-       question. It presents an overview of the
                                                                                                 Given the dynamic nature of juvenile
sis (or windfall). Deteriorating buildings        roles of juvenile justice system policies
                                                                                                 justice policies, anticipating space
may necessitate new construction, or a            and decisionmaking in determining space
                                                                                                 needs in detention and correctional
change in political leadership may bring          needs. It analyzes several methods for
                                                                                                 facilities will always be challenging.
new policies to the juvenile justice sys-         projecting juvenile confinement popula-
                                                                                                 Adoption of the ongoing systematic
tem. No matter what compels State and             tions, noting the limits of simple projec-
                                                                                                 forecasting approach set forth in this
local officials to ask about future bed-          tion models and presenting a detailed ex-
                                                                                                 Bulletin, however, should enable
space, their interest in the answer is            ample of a comprehensive projection
                                                                                                 policymakers to enhance the quality
usually urgent and intense.                       model. The Bulletin goes on to examine
                                                                                                 and usefulness of their projections.
                                                  the practical implications of projecting
Juvenile justice professionals who must           detention and corrections populations
respond to questions about space needs
                                                  and to outline the differences between
may be tempted to answer with simple              forecasting and predicting future space
statistical predictions based on recent
                                                  needs. (The background of the space
trends in juvenile arrests and court com-         needs assessment study discussed in this
mitments or even recent changes in deten-
                                                  Bulletin is summarized on page 2.)
tion and corrections populations. Simple
                                                                                         Space Needs
Background of the OJJDP Space Needs Assessment Study                                     and System
On November 26, 1997, as part of Public Law 105–119, Congress requested that the         Decisionmaking
U.S. Department of Justice conduct a “national assessment of the supply and de-          Anticipating future space needs in juvenile
mand for juvenile detention space,” including an assessment of detention and correc-     detention and correctional facilities can be
tions space needs in 10 States. In particular, Congress expressed this concern:          one of the most difficult challenges faced
                                                                                         by administrators and practitioners. The
   The conferees are concerned that little data exists on the capacity of juvenile
                                                                                         costs of errors can be very high, consider-
   detention and corrections facilities to handle both existing and future needs and
                                                                                         ing the financial investment needed to
   direct the Office of Justice Programs to conduct a national assessment of the
                                                                                         construct and operate new facilities. Un-
   supply of and demand for juvenile detention space with particular emphasis on
                                                                                         derestimating future demands for space
   capacity requirements in New Hampshire, Mississippi, Alaska, Wisconsin, Cali-
                                                                                         can lead to overcrowding, inaccessible
   fornia, Montana, West Virginia, Kentucky, Louisiana, and South Carolina, and to
                                                                                         facilities, and political conflict. Overesti-
   provide a report to the Committees on Appropriations of the House and the
                                                                                         mating future demands can lead to charges
   Senate by July 15, 1998.
                                                                                         of financial mismanagement. In the worst
OJJDP responded to this request by taking two actions. The first action was to submit    case, system officials may be tempted to
a report to Congress in July 1998 (see An Assessment of Space Needs in Juvenile          fill underused facilities with youth who
Detention and Correctional Facilities, Report to Congress, Washington, DC: U.S. De-      would not have been confined if excess
partment of Justice, Office of Justice Programs, Office of Juvenile Justice and Delin-   capacity had not been created.
quency Prevention, July 1998). That report provided some of the background for this
                                                                                         The demand for confinement space is not
Bulletin. It was prepared by OJJDP with assistance from The Urban Institute, the
                                                                                         simply a function of juvenile population
National Center for Juvenile Justice, the National Council on Crime and Delinquency,
                                                                                         trends and juvenile arrest rates. Policy
and The American University in Washington, DC.
                                                                                         decisions will also, in part, determine de-
The second action taken by OJJDP was to fund a more extensive investigation as           mand. For a small number of juvenile of-
part of the Juvenile Accountability Incentive Block Grants (JAIBG) program. The in-      fenders in any jurisdiction, justice system
vestigation, known as the Assessment of Space Needs in Juvenile Detention and            intervention will always require secure
Corrections project, is being completed by researchers at The Urban Institute. The       confinement. Few doubt the need for such
Urban Institute is focusing on the methods used by States to anticipate future de-       confinement in cases involving serious,
mand for juvenile detention and corrections space. Products of the work will include     violent, and chronic offenders; juveniles
new tools to forecast detention and corrections populations at State and local levels.   who have previously failed to appear for
Project advisors and consultants are listed below.                                       scheduled court dates; or youth who
                                                                                         pose a serious danger to the community.
Project Advisory Committee
Dr. Arnold Irvin Barnett, Massachusetts Institute of Technology                          For another relatively small group of
                                                                                         offenders, justice system intervention
Dr. Donna M. Bishop, Northeastern University                                             should almost never involve secure con-
                                                                                         finement. Youth who have not committed
Mr. Edward J. Loughran, Council of Juvenile Correctional Administrators
                                                                                         prior offenses, very young offenders, and
Dr. James P. Lynch, The American University                                              youth charged with nonserious offenses
                                                                                         nearly always should be handled in the
Dr. Samuel L. Myers, Jr., University of Minnesota                                        community. The same is usually true for
Ms. Patricia Puritz, American Bar Association                                            highly vulnerable youth and those with
                                                                                         active, involved families and community
Project Consultants                                                                      support systems that can competently
Mr. Paul DeMuro, Independent Consultant, Montclair, NJ                                   supervise the youth’s behavior.

Dr. William J. Sabol, Case Western Reserve University                                    For a large middle portion of the juvenile
                                                                                         offender population, however, the deci-
Dr. Howard N. Snyder, National Center for Juvenile Justice                               sion as to whether to use confinement
Mr. David J. Steinhart, Independent Consultant, Mill Valley, CA                          is not obvious. It is a complex, uncertain,
                                                                                         and sometimes highly contentious pro-
For more information about this Bulletin or the Assessment of Space Needs in             cess involving a wide assortment of
Juvenile Detention and Corrections project, contact the OJJDP Program Specialist         policymakers, practitioners, and even
responsible for the effort, Joseph Moone, at 202–307–5929 (phone) or                     members of the community. Confinement
moone@ojp.usdoj.gov (e-mail).                                                            decisions depend on the actions and
                                                                                         beliefs of police officers, prosecutors,
                                                                                         judges, probation officers, elected offi-
                                                                                         cials who make policies that allocate re-
                                                                                         sources across the spectrum of juvenile
                                                                                         justice programs, and members of the
                                                                                         community who support or oppose



                                                                   2
those policies by electing some officials      The answers to these questions will vary
and not others.                                from jurisdiction to jurisdiction and will       More Than One Type
                                               be determined by the choices and poli-           of Space
Moreover, the confinement space pro-
                                               cies of a number of agencies. Even the
vided by detention and correctional facili-
                                               first dimension, caseload, is, in part, a        Space, in a juvenile justice context,
ties is just one type of resource available
                                               function of the choices and policies of          is often measured in terms of beds. The
for accomplishing the varied tasks of the
                                               law enforcement agencies. One juris-             number of juveniles that can be held in a
juvenile justice system—preventing ju-
                                               diction, for example, may arrest every           detention or correctional facility is equal
venile crime, rehabilitating individual
                                               youth caught with even the smallest              to its sleeping capacity. Thus, policy dis-
offenders, controlling the behavior of of-
                                               amount of marijuana, while another may           cussions about juvenile justice program
fenders, and holding offenders account-
                                               elect to use unofficial diversion for every      resources often focus on the availability
able for their behavior through the use
                                               first-time offender possessing less than         of “bedspace.”
of sanctions. Each of these responsibili-
                                               an ounce. The second and third dimen-
ties may sometimes involve the use of
                                               sions, process and preferences, are ex-          Bedspace Sometimes a
secure confinement, but none always re-
                                               clusively shaped by policy choices, in-
quires it. Even controlling offender behav-                                                     Misnomer
                                               cluding the statutory choices of elected
ior and holding youth accountable can be                                                        Bedspace, however, can be a misno-
                                               officials.
achieved in certain cases without the use                                                       mer if the term is used too generally.
of incarceration. Each jurisdiction’s par-     Every young offender presents a chal-            The number of beds available in a
ticular combination of incarceration and       lenge for juvenile justice officials. Which      jurisdiction is not equal to its juvenile
nonincarceration is a function of its expe-    program options are best? What are the           justice program resources. Some
riences, resources, values, and policy         most cost-effective available options, not       programs can effectively supervise,
choices. (See “More Than One Type of           only for ensuring the safety of the public       control, and hold young offenders ac-
Space” on this page.)                          but also for preserving the chances of           countable without requiring them to be
                                               youth to have positive and productive            in residence for 24 hours each day.
Appropriate Confinement                        lives? Every decision has ramifications.
                                               Some are direct and immediately appar-           Nonresidential programs may include
Decisions                                                                                       home detention, intensive supervision,
                                               ent. Others are indirect and difficult to
Every State or local jurisdiction with a       notice in the short term.                        electronic monitoring, day reporting,
juvenile justice system must build and                                                          and vocational training. Young offend-
manage a system that responds effec-                                                            ers may spend much of their day un-
tively to the actual (and, to some extent,     Impact of Preferences                            der the control of these programs but
perceived) level of juvenile crime in the      and Policies                                     then return to their own homes to
community. To build an effective system,       Decisions made by legislators, judges,           sleep at night.
policymakers must regularly receive in-        police and probation officials, social
formation about the volume and charac-         workers, and juvenile facility administra-       Effective Policy Requires
teristics of the juvenile offender popula-     tors help to determine which juvenile
tion in their jurisdictions, the quality and
                                                                                                a Broader View
                                               offenders are placed in detention or cor-
availability of their juvenile justice re-     rectional facilities, when they are placed,      To assess the validity of demands for
sources, and the mix of those resources,       and how long they stay. Some factors in-         additional bedspace, policymakers
both residential and nonresidential.           volved in these decisions are similar to         need information about all resources
                                               the factors involved in adult jail and           available in a juvenile justice system,
Confinement decisions can be best un-                                                           not only the amount of residential
                                               prison commitments. These include the
derstood by analyzing three dimensions:                                                         bedspace.
                                               severity of each offender’s most recent
x Caseload. How many offenders are             offense and the extent and severity of his       Ultimately, the need for additional
  coming into the juvenile justice sys-        or her record. The juvenile justice sys-         bedspace in a jurisdiction is related to
  tem? What are the characteristics of         tem, however, often has more discretion
  those offenders from either a public         in responding to these factors. For ex-          x The number of juveniles requiring
  safety or rehabilitation perspective?        ample, juvenile courts may sometimes               treatment, supervision, and control.
                                               place offenders in secure custody for
x Process. What decisions does the juve-                                                        x The availability and quality of exist-
                                               their own protection and hold offenders
  nile justice system make concerning                                                             ing bedspace.
                                               in custody because they failed to appear
  the handling of individual offenders?
                                               for court hearings when released on pre-         x The availability, quality, and use of
  Who is involved in decisionmaking,
                                               vious charges.                                     nonresidential program resources.
  and what information is used to reach
  decisions in individual cases?               Some aspects of juvenile justice decision-
x Preferences. What program options            making may be unique to the juvenile jus-
                                               tice system. Considerations that would be      part because the youth is thought to have
  are available for implementing deci-                                                        a drug abuse problem, although no drug
  sions made within the juvenile justice       prohibited in the criminal justice system
                                               may influence a decision to place a youth      charges may be involved in the case. A
  system? Who is involved in selecting                                                        juvenile with a precarious family situation
  and supporting available program op-         in a secure facility. A juvenile court judge
                                               may decide to detain a youth or commit         and chaotic home environment may be
  tions, what information do they use,                                                        placed in a secure setting to ensure the
  and what values and beliefs underlie         him or her to a correctional facility in
                                                                                              delivery of social services.
  their choices?


                                                                    3
Placement decisions may also be influ-
enced by the availability and perceived         Figure 1: Using population alone, an analyst working in 1970 would
adequacy of program alternatives. Place-                  have recommended no expansion in detention and correc-
ment rates may be higher when juvenile                    tions space through the 1990’s—yet the number of delin-
courts have fewer nonresidential options
                                                          quency cases nationwide doubled during that period
to draw on in lieu of placement (e.g., in
rural areas and impoverished communi-
                                                                                       120
ties). For these reasons, the use of se-
cure confinement in the juvenile justice
system is rarely a straightforward conse-




                                                         Change Relative to 1970 (%)
quence of trends in juvenile populations
and crime rates. Some researchers might                                                 80
even argue that a statistical model would                                                        Delinquency cases handled
perform better using the availability of                                                           by U.S. juvenile courts
bedspace to predict juvenile placement
decisions than it would using placement                                                 40
decisions to predict bedspace.


Projections of                                                                           0
Juvenile Confinement
Populations                                                                                        U.S. population ages 10–17
Sound projections require high-quality                                                 – 40
data. Without data, policymakers have                                                     1970   1974   1978   1982   1986      1990   1994   1998
only the opinions and beliefs of practi-
tioners and administrators with which                                                                             Year
to project future needs for bedspace.
                                                x Between 1970 and 2000, the U.S. juvenile population declined from 32 million to 27
The superintendent of a detention center          million, then rebounded to nearly 32 million again.
may offer his or her personal observa-          x Between 1970 and 1997, the number of delinquency cases handled by the Nation’s
tions about crowding in detention. The            juvenile courts more than doubled, from approximately 800,000 to nearly 1.8 million
administrator of a corrections facility           annually.
may observe that young offenders are            Source: Data from U.S. Bureau of the Census’ National Residential Population Estimates
being placed on waiting lists because of        series and the National Center for Juvenile Justice’s (NCJJ’s) National Juvenile Court Data
insufficient space. A county sheriff may        Archive (NJCDA). For population estimates prior to 1980, see 1970 Census of the Population,
complain that officers are required to          Vol. 1. Characteristics of the Population, Part 1: United States Summary, Section 1, U.S.
transport youth to a neighboring juris-         Department of Commerce, Bureau of the Census, June 1973. Estimates for 1971–79 were
                                                interpolated using 1970 and 1980 single-year age estimates and 1975 estimates for grouped
diction to find an opening in a secure          ages. NJCDA national estimates prior to 1975 included status offenses. The average delin-
facility. Although personal observations        quency proportion of the delinquency/status totals for 1975–79 was used to adjust NJCDA
may be helpful in making projections,           data before 1975.
relying on anecdotal information alone
may result in costly errors. Each indi-
vidual involved in the juvenile justice      fund an additional 50-percent increase in                             For example, researchers could analyze
process can explain the process only         corrections space over the next 10 years,                             trends in the use of waiting lists and
from his or her unique perspective.          but this could be a poor decision. Obvi-                              early releases from confinement. An in-
Few are aware of every aspect of the         ously, a jurisdiction that increased its                              crease in these practices may indicate a
process and of the complex interactions      bedspace significantly in 1999 should not                             growing demand for space. Even this in-
between decisions made at various            rely on the increase in admissions from                               formation, however, does not eliminate
points in the process.                       1998 to 2000 to argue for yet more bed-                               the risk of misinterpretation. The fact
                                             space in 2001. Similarly, it would be un-                             that a juvenile detention center is con-
Once policymakers decide to look beyond      fair to use the lack of an increase to argue                          stantly full with no waiting lists or early
personal opinions, they need data about      that an agency does not require addi-                                 releases could have more than one ex-
the use of detention and corrections         tional space. Perhaps a jurisdiction has                              planation. It could mean that available
space. Unfortunately, the easiest informa-   not funded any new corrections space                                  space is precisely equal to demand, or
tion to assemble is rarely ideal. In some    during the past 20 years. Flat funding                                it could mean that local decisionmakers
jurisdictions, the only readily available    would explain the jurisdiction’s flat ad-                             have learned to refer just enough youth
data may be about past uses of detention     mission numbers, but this would not                                   to detention so that a facility remains
and corrections space. An agency might       necessarily mean that additional space                                full without being oversubscribed.
only know that admissions to juvenile        is unwarranted.
corrections grew 50 percent during the                                                                             What would policymakers conclude if
past 10 years. Some policymakers might       Policymakers are better served when agen-                             the same correctional facility suddenly
interpret this as a legitimate reason to     cies can generate additional information.                             began to report crowding, early releases,




                                                                                             4
                                                                                                          commonly used by State and local agen-
   Figure 2: Predictions based on arrests since 1980 would have been                                      cies is to monitor trends in juvenile ar-
             very different depending on when they were generated                                         rests and then estimate future demand
                                                                                                          for detention and corrections space
                              160,000                                                                     based on expected changes in the num-
                                                                                                          ber of arrests. For example, some juris-
                              140,000                                                                     dictions base their projections on
                                                                                                          trends in juvenile arrests for the most
          Number of Arrests




                              120,000                                                                     serious offenses, such as the Federal
                                                                                                          Bureau of Investigation (FBI) Violent
                              100,000                                                                     Crime Index offenses (i.e., murder and
                               80,000                                                                     nonnegligent manslaughter, forcible
                                                       Juvenile arrests for FBI Violent                   rape, aggravated assault, and robbery).
                                                           Crime Index offenses                           The logic behind this approach is that
                               60,000
                                                                                                          youth charged with violent and other
                               40,000                                                                     serious offenses generate most of the
                                                                                                          space needs in any jurisdiction.
                               20,000
                                                                                                          The complexity of juvenile justice decision-
                                   0                                                                      making, however, virtually guarantees
                                   1980 1982 1984 1986 1988 1990 1992 1994 1996 1998                      that detention and corrections popula-
                                                                                                          tions will not follow Violent Crime Index
                                                              Year                                        arrest trends so closely. National changes
                                                                                                          in juvenile arrests during the 1990’s un-
   Five-Year Trend Predictions as Calculated in 1985, 1990, and 1993                                      derscore this point. The 1990’s were a
                                                                                                          virtual case study in how difficult it can
                                                       Predicted
   Date of                            Change in         Arrests           Actual Arrests                  be to predict juvenile justice trends. No
   Prediction                      Prior 5 Years (%)   in 5 Years           in 5 Years       Error        statistical model could have anticipated
                                                                                                          the changes in serious juvenile crime that
   1985                                  –9              76,100              114,200       33% under      occurred between 1985 and the end of the
   1990                                  37             156,400              147,700        6% over       1990’s (figure 2).
   1993                                  49             206,100              112,200       84% over
                                                                                                          Consider what would have happened if
   Source: Data from the FBI’s Crime in the United States annual series. National estimates               an analyst working in 1985 had projected
   calculated by The Urban Institute using methods developed by NCJJ (see Snyder, 1999).                  changes in the nationwide demand for
                                                                                                          bedspace using 5-year trends in FBI Vio-
                                                                                                          lent Crime Index arrests. The projection
and waiting lists for admission? Such a                     detention beds and its juvenile popula-       of bedspace needs in 1990 would have
development might indicate an increase                      tion is expected to increase 20 percent       been produced by multiplying 1985 lev-
in juvenile crime and the need for more                     over the next 10 years, policymakers          els of placement resources by the per-
space, or it might mean that local au-                      might recommend expanding detention           centage change in Violent Crime Index
thorities had decided to begin referring                    capacity to 120 beds over the same pe-        arrests between 1980 and 1985—a de-
all potential detention cases for place-                    riod. This approach may be an improve-        crease of 9 percent. Arrests for violent
ment and not concern themselves with                        ment in a jurisdiction that has previously    offenses, however, were about to jump
availability. Projecting future space                       used only anecdotal methods to antici-        sharply. A projection from 1985 would
needs requires more extensive analysis.                     pate future space needs, but it has great     have underestimated the volume of ar-
The question is what type of analysis?                      potential for error. Consider the fact that   rests in 1990 by 33 percent. An analyst
                                                            the national population of juveniles was      working in 1990 would have been more
Limits of Simple Models                                     relatively unchanged between 1970 and         fortunate using the percentage change in
                                                            1998, a period when juvenile court case-      arrests from 1985 to 1990 (up 37 percent)
Juvenile justice agencies often begin                                                                     to project space needs in 1995. Yet, a few
                                                            loads more than doubled. An analyst
their efforts to project detention and                                                                    years later, in 1993, the same technique
                                                            working with population data alone in
corrections populations with relatively                                                                   would have produced estimates for 1998
                                                            the 1970’s or 1980’s could have produced
simple models. Simple models may pro-                                                                     that were far larger than actual need.
                                                            very misleading projections (figure 1).
vide projections quickly and at relatively                                                                No statistician using this method in 1993
little cost, but they can also produce                      Most juvenile justice administrators          would have predicted that juvenile ar-
misleading information. One of the most                     know that projection efforts must in-         rests for violent offenses would drop
common simple models assesses the                           clude at least some data about the juve-      25 percent between 1994 and 1998.
need for secure confinement resources                       nile justice process because the number
according to expected changes in the                        of offenders referred for placement can       Extending the period of calculation by
juvenile population (e.g., youth ages 10                    differ considerably from trends in the        using 10-year trends rather than 5-year
through 17). If a jurisdiction has 100                      juvenile population. One approach             trends would ameliorate the problem




                                                                                   5
                                                                                                                            than 1 million delinquency cases in 1980,
   Figure 3: Predictions based on arrests since 1980 would fail to account                                                  just half the number of arrests involving
             for changes in how juvenile arrests were processed by                                                          youth younger than age 18 that year. By
             prosecutors and the courts                                                                                     1997, the total number of delinquency
                                                                                                                            cases handled by juvenile courts re-
                                                 90                                                                         presented 62 percent of the number of
         Juvenile Arrests (National Estimates)
         Delinquency Cases as Percentage of




                                                                                                                            arrests.1
                                                                                                                            Law enforcement’s increasing use of
                                                 80                                                                         court referrals for arrested youth is also
                                                       FBI Crime Index offenses                                             apparent when the analysis examines
                                                                                                                            only court cases and arrests that in-
                                                 70                                                                         volved FBI Crime Index offenses (i.e.,
                                                                                                                            all offenses on the Violent and Property
                                                                                                                            Crime Indexes). In the early 1980’s, the
                                                 60                                                                         number of court cases involving Crime
                                                          All offenses                                                      Index offenses equaled about 70 percent
                                                                                                                            of the number of juvenile arrests involv-
                                                 50                                                                         ing Crime Index offenses. By the late
                                                                                                                            1990’s, the number of juvenile court
                                                                                                                            cases involving these offenses repre-
                                                 40                                                                         sented nearly 90 percent of the number
                                                  1980 1982 1984 1986 1988 1990 1992 1994 1996 1998                         of arrests.

                                                                               Year                                         Projection efforts are more useful if they
                                                                                                                            can account for changing patterns in
   Delinquency Cases and Juvenile Arrests: 1980, 1990, and 1997                                                             court processing. A changing rate of
                                                                  1980                     1990                1997         formal prosecution in juvenile courts, for
                                                                                                                            example, could have a dramatic effect on
   All offenses                                                                                                             the number of youthful offenders placed
   Juvenile arrests                                             2,166,600                2,214,500           2,838,300      in secure facilities. National data about
   Delinquency cases                                            1,089,500                1,318,000           1,755,100      juvenile court processing reveal, in fact,
   Ratio of arrests to cases                                        2 to 1                  1.7 to 1            1.6 to 1    that the proportion of delinquency cases
                                                                                                                            handled formally (with prosecutor peti-
   Index offenses
                                                                                                                            tions rather than informal agreements
   Juvenile arrests                                               839,900                  822,800             824,900
                                                                                                                            for diversion or dismissals) increased
   Delinquency cases                                              544,900                  631,300             705,100      from 49 percent to 57 percent between
   Ratio of arrests to cases                                       1.5 to 1                 1.3 to 1            1.2 to 1    1983 and 1997 (figure 4).

   Source: Data from NCJJ’s National Juvenile Court Data Archive and the FBI’s Crime in the
                                                                                                                            This shift toward more formal handling
   United States annual series. National estimates calculated by The Urban Institute using                                  could have been expected to increase
   methods developed by NCJJ.                                                                                               the number of juveniles eligible for out-
                                                                                                                            of-home placement. An analyst project-
                                                                                                                            ing future space needs with this infor-
                                                                                                                            mation might still have made significant
somewhat but not resolve it entirely                                          charged with delinquency, adjudicated         errors, however, unless the analysis
because the number of arrests is not di-                                      a delinquent, and then committed by the       was amended to include an additional
rectly linked to the number of place-                                         court. Thus, changes in detention and         factor—namely, changes in the use of
ments. Analysts will produce more useful                                      corrections populations are likely to be      formal adjudication. Between 1983 and
projections when they include juvenile                                        more closely related to changing court        1997, as the use of formal petitioning
court processing data in projection mod-                                      actions than to changes in juvenile           increased, the use of adjudication saw
els. The juvenile court process is the                                        arrests.                                      a corresponding decrease from 68 per-
principal gatekeeper for placements in                                                                                      cent to 58 percent. When both changes
                                                                              This is clear when trends in juvenile ar-
juvenile bedspace. The juvenile court                                                                                       are considered together, it is clear that
usually approves detention decisions, or                                      rests are compared over time with trends
                                                                              in juvenile court delinquency cases (fig-     the total rate of adjudication (adjudi-
at least it must approve the continuation                                                                                   cation as a percentage of referrals) re-
of detention beyond some statutorily de-                                      ure 3). Between 1980 and 1997, for ex-
                                                                              ample, increases in delinquency cases         mained unchanged between 1983 and
fined limit (e.g., 72 hours). The juvenile                                                                                  1997 (33 percent in both years). This ex-
court is also the main access point for                                       outpaced increases in juvenile arrests.
                                                                              According to the Office of Juvenile Justice   ample demonstrates that projection
placement in (or commitment to) long-                                                                                       models are likely to perform better
term facilities. To be admitted to a juve-                                    and Delinquency Prevention’s (OJJDP’s)
                                                                              Juvenile Court Statistics program at the      when they include more than a single
nile correctional facility, young offenders                                                                                 source of information and when they
must be referred to court, officially                                         National Center for Juvenile Justice, U.S.
                                                                              juvenile courts handled slightly more



                                                                                                       6
analyze more than a single point in the
juvenile justice process.                              Figure 4: Despite changing patterns in the handling of delinquency
                                                                 cases between 1983 and 1997, the overall use of adjudication
Example: Projecting the                                          and out-of-home placement remained relatively consistent
Juvenile Commitment
Population in 2002                                                                  70
                                                                                                                  Adjudications as percentage
The following section presents an ex-                                                                             of formally petitioned cases




                                                              Percentage of Cases
ample of a projection model using data                                              60
about the national population of juvenile
offenders committed to residential facili-                                          50
ties.2 The analysis provides several differ-                                                                Formal petitions as percentage
ent projections, each based on a different                                                                  of referred delinquency cases
set of assumptions. The results from each                                           40
set of assumptions reveal the sensitivity
of population projections to changes in                                             30
policy and practice, including changes in                                                           Out-of-home placements as
the rate of referral, the rate of adjudica-                                                         percentage of adjudicated cases
tion, the number of out-of-home place-                                              20
ments, and the average length of those                                              1983     1985   1987   1989     1991    1993    1995    1997
placements. The range of projections                                                                          Year
based on these varying assumptions
helps to set upper and lower bounds on                x In 1983, 49 percent of delinquency cases were formally petitioned and 68 percent of these
the future size of the national commit-                 were adjudicated, resulting in a total adjudication rate of 33 percent.
ment population. The analysis uses data               x In 1997, a 57-percent petition rate and 58-percent adjudication rate again resulted in a
from 1993 to 1997 to project populations                total adjudication rate of 33 percent.
through 2002. The results suggest that a              x The use of out-of-home placement was relatively consistent between 1983 and 1997,
major determinant of change in the com-                 varying between 28 and 32 percent of adjudicated cases throughout the period.
mitment population originates outside                 Source: Data from NCJJ’s National Juvenile Court Data Archive.




  Delinquency Case Processing, 1993–97
  The number of juveniles in commit-               Adjudication                                                x For person crimes, the use of residen-
  ment increased from 37,700 in 1993 to            x Between 1993 and 1997, the number of                        tial placement dropped from 35 to 32
  52,500 in 1997. The increase was due               cases resulting in adjudication increased                   percent of adjudications.
  to a number of factors—the growth in               26 percent.
  the number of referrals to juvenile court,                                                                   Length of Stay
  changes in the rate of adjudication,             x The number of adjudicated cases in-
                                                     creased in every major offense category.                  x The average length of stay for com-
  changes in the rate of residential place-
                                                                                                                 mitted juveniles increased 14 percent
  ment, and changes in lengths of stay.
                                                   x The rate of adjudication (the number                        between 1993 and 1997, from 96 to
                                                     of adjudications divided by referrals) in-                  109 days.
  Referral                                           creased 2 percent. The rate was stable
  x The total number of delinquency cases            for all major offense categories.                         x Most of the growth in length of stay
                                                                                                                 was driven by person crime offenders
    referred to juvenile courts that involved
    youth ages 10 to 17 increased 19 per-                                                                        (whose average length of stay in-
                                                   Placement                                                     creased from 162 to 180 days) and
    cent between 1993 and 1997, from
                                                   x From 1993 to 1997, the percentage of                        by property crime offenders (89 to
    approximately 1.4 to nearly 1.7 million.
                                                     adjudicated cases involving youth ages                      104 days).
  x Cases involving property offenses ac-            10 to 17 that resulted in residential place-
    counted for half of all court referrals in       ment was relatively stable at 31 to 32                    x Length of stay increased from 22 to
                                                     percent.                                                    49 days for public order offenders and
    both years.
                                                                                                                 decreased from 148 to 113 days for
  x The rate of growth was largest among           x The use of placement was constant for                       drug offenders.
    drug cases, which more than doubled,             property and public order offenses. For
    and for public order offenses, which             drug offenses, the use of placement
    grew more than 30 percent.                       decreased from 32 to 27 percent.

  Note: These data differ from other published analyses of National Juvenile Court Data Archive data because cases involving youth under age 10 or
  older than age 17 are excluded, as are technical violation cases. Percent changes were calculated using unrounded numbers.
  Source: Urban Institute analysis of data from NCJJ’s National Juvenile Court Data Archive. National estimates of delinquency cases involving youth
  ages 10 to 17.



                                                                                         7
                                                                                                          probation are excluded. After making
Table 1: Juvenile Offenders in Residential Placement, 1993–97                                             these adjustments, the analysis suggests
                                                                                                          that the juvenile commitment population
                                         One-Day Count of Juvenile Offenders in Custody                   increased 39 percent between 1993 and
                                                   (delinquency offenses only)                            1997, from 37,700 to 52,500.
   Population                                   1993                  1995               1997             To generate estimates of the future com-
                                                                                                          mitment population, a statistical flow
   Total population of juveniles                                                                          model is used that analyzes the process-
   committed to residential                                                                               ing of delinquency cases to the point
   placement                                   52,000               59,500             71,700             of placement and models the lengths
   Private-facility-adjusted                                                                              of stay in placement. The model begins
   population*                                 55,200               61,600             71,700             with a starting population and calculates
   Age-adjusted population†                    37,700               43,500             52,500             transition rates (or probabilities that
                                                                                                          cases will move from one stage of the
   Person offenders                            14,800                18,300             19,800
                                                                                                          juvenile justice process to the next). The
   Property offenders                          16,600                17,800             21,300            flow model includes the following stages:
   Drug offenders                                4,300                4,600              5,500            (1) referral to juvenile court, (2) adjudi-
   Public order offenders                        1,900                2,800              5,900            cation, (3) commitment to residential
                                                                                                          placement, and (4) length of stay for
* Adjustments were made to 1993 and 1995 committed populations to compensate for undercounts
of juveniles in placement in private facilities in those years. This was done by applying the ratio of    youth in residential placement. Transi-
delinquent youth in private facilities to delinquent youth in public facilities in 1997 to the reported   tion probabilities include the adjudica-
population of youth in public facilities in 1993 and 1995, respectively, to obtain an estimate of the     tion rate (the percentage of referred
number of delinquent youth in private facilities for those years. These estimates were added to the       cases that are adjudicated), the use of
reported number of delinquent youth in public facilities for 1993 and 1995, respectively, to obtain       residential placement (the percentage
private-facility-adjusted commitment populations for each year.                                           of adjudicated cases that are committed
† The Children in Custody (CIC) census for 1993 and 1995 does not disaggregate committed and              to residential facilities), and the average
detained delinquent populations by age. To obtain this information for youth ages 10–17, offense-         length of stay in facilities (measured as
specific adjustments were made based on the proportion of 10- to 17-year-olds in the overall              a stock-to-flow ratio; see discussion of
detained and committed populations in 1997, which is provided by OJJDP’s Census of Juveniles in
Residential Placement 1997. The assumption is that the proportion of 10- to 17-year-olds in the           length of stay, pages 12–13).6 These tran-
detained and committed populations in 1993 and 1995 was the same as that actually observed in             sition probabilities are shown in table 2.
1997. This assumption is supported by the age distribution of the overall custody population during
1993–97, which remained quite stable. (CIC data provide the age distribution for the overall juvenile     Changes in the commitment population
custody population but do not distinguish between offenders and nonoffenders or between delin-            can be shaped by a variety of case pro-
quent and status offenders. The universe for this study is delinquent offenders only.) The 10- to         cessing components, including the num-
17-year-old portion of the overall custody population was remarkably stable during 1993–97: 87.4          ber of juvenile court referrals, the per-
percent in 1993, 87.8 percent in 1995, and 87.5 percent in 1997. These age-adjusted custody               centage of those referrals that result in
populations also exclude youth in facilities for technical violations.
                                                                                                          adjudication, the number of those cases
Note: Detail may not add to totals due to rounding. These counts include committed youth only;            that end in residential placement, and
detained youth are excluded.                                                                              the length of those placements. As these
                                                                                                          components increase or decrease, they
Source: NCJJ analysis of OJJDP’s Children in Custody census 1993 and 1995 data files and
OJJDP’s Census of Juveniles in Residential Placement 1997 data file.                                      exert an influence on the size of the com-
                                                                                                          mitment population. It is possible to iso-
                                                                                                          late the changes in each component and
                                                                                                          determine the share of the total change
the juvenile court—namely, the number of              data most likely underestimate the num-
                                                                                                          in the commitment population for which
referrals by law enforcement. The relative            ber of juveniles in private facilities during
                                                                                                          each is responsible (see Methodology on
rates of adjudication and placement and               the 1993–95 period. Adjusting for this
                                                                                                          page 17). Certain components may con-
changes in average lengths of stay also               undercount produces slightly higher fig-
                                                                                                          tribute to growth, while others may have
affect the size of commitment populations.            ures.4 The data are also adjusted to ac-
                                                                                                          the opposite effect. For example, if the
(Trends in these components of delin-                 count for the fact that although many
                                                                                                          number of court referrals increases, this
quency case processing between 1993                   youth in the commitment population at
                                                                                                          will contribute to an expansion of the
and 1997 are summarized on page 7.)                   any given time are older than 17, very few
                                                                                                          commitment population. At the same
                                                      are older than 17 at the time of their com-
According to data collected for OJJDP by                                                                  time, other elements of the system could
                                                      mitment. Adjusting the data for age allows
the U.S. Bureau of the Census, the daily                                                                  curtail growth. A decrease in the use of
                                                      the analysis to compare more directly the
size of the committed juvenile population                                                                 placement could offset part or all of the
                                                      data on commitment populations with
in custody for delinquency offenses in-                                                                   growth generated by increasing referrals.
                                                      data on commitment admissions.5 The
creased 38 percent between 1993 and 1997,                                                                 Adding up the “shares” from all compo-
                                                      analysis also limits the commitment
from 52,000 to 71,700 (see table 1). For this                                                             nents of juvenile justice case processing
                                                      population to juveniles who were placed in
example, however, several adjustments to                                                                  yields the overall net change in the com-
                                                      residential facilities for new offenses. Juve-
these data are necessary.3 First, the raw                                                                 mitment population.
                                                      niles committed for technical violations of




                                                                              8
Table 2: Referrals to Juvenile Court and Transition Probabilities for Youth in Residential Placement, 1993 and 1997

                                                                                                   Rate of
                             Number of Referrals                          Rate of                Residential                        Length of Stay
                              to Juvenile Court                       Adjudication (%)         Placement (%)*                     (stock/flow ratio)†
                                                    Change                                                                1993         1997        Change
   Offense             1993            1997           (%)              1993         1997        1993        1997         (days)       (days)         (%)
   Total            1,427,600      1,693,600            19              31          33              32       31           96           109            14
   Person              309,200        378,200           22              31           33             35        32         162           180            11
   Property            784,000        812,600            4              30           32             29        29          89           104            17
   Drug                 86,200        177,300         106               37           37             33        27         148           113           –24
   Public order        248,200        325,500          31               34           37             37        37          22            49           123

* Percentage of adjudicated cases committed to residential facilities.
† Stock/flow ratio of the number of juveniles in residential facilities divided by the number of cases resulting in residential placement during the year.
The ratio is converted to the unit of days.
Source: OJJDP’s Children in Custody census 1993 data file, OJJDP’s Census of Juveniles in Residential Placement 1997 data file, and NCJJ’s National
Juvenile Court Data Archive 1993 and 1997 data files.



Table 3 and figure 5 show how each com-
ponent of the system contributed to the                 Table 3: Change in Number of Juveniles Committed to Residential
amount of overall change in the commit-                          Placement Between 1993 and 1997, by Category of Offense and
ment population between 1993 and 1997.                           Components of Change
Several factors contributed to the expan-
sion of this population from 37,700 to                                                     Number of Juveniles Committed
52,500 juveniles. Increases in the number
of court referrals, the rate of adjudica-                    Offense                         1993                        1997                  Net Change
tion, and the average length of stay all
                                                             Total                          37,700                       52,500                 14,900
contributed to the expansion, while the
decrease in the use of residential place-                    Person                         14,800                       19,800                  4,900
ment had a curtailing effect.                                Property                       16,600                       21,300                   4,700
Of the four major offense categories (per-                   Drug                            4,300                        5,500                   1,300
son, property, drugs, public order), person                  Public order                    1,900                        5,900                   4,000
and property offenses accounted for most
(each about one-third) of the total change
in the commitment population. Increases                                      Change in the Juvenile Commitment Population
in the number of commitments for public                                             Between 1993 and 1997 Due To:
order and drug offenses accounted for ap-                                                                      Use of           Length
proximately 27 percent and 9 percent, re-                    Offense         Referral       Adjudication     Placement          of Stay      Net Change
spectively, of the change in the commit-
ment population.                                             Total            9,000            1,800           –2,600             6,600         14,900
                                                             Person           3,300              900           –1,200             2,000          4,900
Increases in length of stay accounted for
80 percent of the growth in the commit-                      Property           600              900              100            3,200            4,700
ment population of offenders charged                         Drug             4,500             –100           –1,700           –1,500            1,300
with public order offenses. For those                        Public order       600              200                 0            3,200           4,000
charged with drug offenses, increases
in the number of youth referred—which                  Note: Detail may not add to totals due to rounding. Calculations were based on unrounded numbers.
more than doubled between 1993 and
1997—overrode the generally downward                   Source: OJJDP’s Children in Custody census 1993 data file, OJJDP’s Census of Juveniles in
                                                       Residential Placement 1997 data file, and NCJJ’s National Juvenile Court Data Archive 1993 and
trend of all other transition probabilities            1997 data files.




                                                                                9
   Figure 5: How much did each source of change contribute to the overall change in the population of juveniles
             in commitment from 1993 to 1997?
      Overall Age-Adjusted Commitment Population




                                                   60,000                                         Combined effect of components of change in commitment population from
                                                                              (52,500)            1993 to 1997
                                                                                                    Court referrals
                                                   50,000                                           An increase of 19 percent in juvenile court referrals accounted for 9,000 of
                                                                                                    the net increase of 14,900 juveniles in the commitment population.

                                                   40,000   (37,700)                                Cases adjudicated
                                                                                                    An increased rate of adjudication (from 31 to 33 percent) accounted for
                                                                                                    1,800 of the net increase of 14,900 in the commitment population.
                                                   30,000
                                                                                                    Use of residential placement
                                                                                                    A decrease in the percentage of adjudicated cases committed to residential
                                                                                                    placement (from 32 to 31 percent) curtailed growth in the commitment
                                                   20,000                                           population by 2,600 juveniles.

                                                                                                    Length of stay
                                                   10,000                                           An increase in average length of stay (from 96 to 109 days) accounted for
                                                                                                    6,600 of the net increase of 14,900 juveniles in the commitment population.

                                                       0
                                                            1993               1997

                                                                       Year
   Note: Components of change may not add to total due to rounding.
   Source: Urban Institute analysis of OJJDP’s Census of Juveniles in Residential Placement 1997 data file, OJJDP’s Children in Custody census
   1993 data file, and NCJJ’s National Juvenile Court Data Archive 1993 and 1997 data files.




(the adjudication rate, the use of place-                                             Will average length of stay increase or             Conditions in the juvenile justice sys-
ment, and average length of stay) associ-                                             decrease? Assumptions about how these               tem rarely remain unchanged for sev-
ated with these offenders. Although                                                   components will or will not change after            eral years at a time. There are specific
there were minor offense-specific varia-                                              1997 have a significant effect on projec-           reasons to doubt that the conditions
tions from the overall sources of change,                                             tions of the juvenile population in facili-         of 1997 would continue for very long
all of the major offense categories con-                                              ties. The following analysis considers sev-         beyond 1997. First, the commitment
tributed to the increase in the number of                                             eral possible scenarios to project a range          population was growing at an increas-
juveniles committed to residential facili-                                            of 2002 commitment populations.                     ing rate between 1993 and 1997. Sec-
ties (table 3).                                                                                                                           ond, the number of cases referred to
                                                                                      Five projections of the commitment popu-            juvenile courts also increased, and this
The commitment population through                                                     lation were developed, each based on a
                                                                                                                                          was responsible for a large part of the
2002 is projected in the analysis by using                                            different set of assumptions (figure 6).            total increase in the commitment popu-
a mathematical flow model based on the                                                These projections (referred to as A, B, C,
                                                                                                                                          lation. In addition, the average length
approach first developed by Stollmack                                                 D, and E) yield commitment populations              of stay changed between 1993 and 1997,
(1973) to project prison populations (see                                             ranging from almost 53,000 to more than
                                                                                                                                          growing from 96 to 109 days. Improb-
“A Brief History of Corrections Population                                            102,000 by the year 2002 (figure 7). For            able changes in case processing would
Projection Methods” on page 14). Future                                               example, if 1997 conditions were to per-
                                                                                                                                          have had to occur for admissions and
populations are projected by relating                                                 sist for 5 years after 1997 (projection A),         length of stay to have remained con-
flows to stocks by length of stay—the in-                                             the number of juveniles in commitment
                                                                                                                                          stant after 1997. For admissions to sta-
verse of which represents the turnover                                                facilities in 2002 would be expected to             bilize, for example, the increase in the
rate of the population. The model re-                                                 remain at the 1997 level (about 53,000 ju-
                                                                                                                                          number of referrals to juvenile court
quires explicit assumptions about the                                                 veniles). In other words, if juvenile courts        between 1993 and 1997 would have had
case processing factors that might influ-                                             were to continue to commit juveniles to
                                                                                                                                          to reverse itself after 1997 or the use of
ence the size of confinement populations.                                             residential placement at the 1997 rate, to          residential placement would have had
For example, the model must include as-                                               adjudicate cases at the 1997 rate, and to
                                                                                                                                          to decrease sharply. These changes
sumptions about changes in referrals and                                              hold juveniles in facilities for an average         are unlikely, given trends observed
length of stay. Will the number of court                                              of 109 days, just as in 1997, the commit-
                                                                                                                                          between 1993 and 1997.
referrals continue to rise through the year                                           ment population would remain at the 1997
2002, or will it stabilize at the 1997 level?                                         level.




                                                                                                           10
On the other hand, if changes in case-
processing practices were incorporated                             Figure 6: Five assumptions are used to define alternative projections
into the projections, the expected popu-                                     of the juvenile commitment population, 1998–2002
lation could follow the paths of projec-
tion lines B, C, D, or E. These projections                                                                          Assuming admissions        Projecting admissions based
show how the juvenile population in                                                                                   remain at 1997 level          on 1993–97 changes
residential placement would change
based on varying assumptions about                                                   Assuming average length
admissions and the average length of                                                                                      Projection A                Projection B
                                                                                 of stay remains at 1997 level.
stay for committed youth. Under projec-
tion B (stable length of stay, admission
                                                                   Projecting average length of stay                      Projection C                Projection D
trends continue), the population would
                                                                       based on 1993–97 changes.
increase to almost 69,000 in the year
2002. Under projection C (stable admis-
sions, trends continue in length of stay),                                        Fixing length of stay for drug                                      Projection E
the population would grow to about                                                 cases to increase 5 percent
75,000 by 2002. Projection D shows how                                              annually; projecting length
the population would change given the                                             of stay for all nondrug cases
assumption that admissions and length                                             based on 1993–97 changes.
of stay each continue the trend observed
from 1993 to 1997. It projects that the
commitment population would grow at
a steep rate, increasing to just more than
98,000 by 2002.                                                   Figure 7: Projections of the juvenile commitment population vary
These projections point out the impor-                                      greatly according to assumptions about future conditions
tance of the key policy variables (the rate
of referral to court, the rate of adjudica-                                      120,000
                                                                                                                                                  Projected commitment
tion, the use of placement, and the length                                                                                                          population, 2002
of stay of youth in residential placement)
in anticipating future demand for bed-                                                                                                                       (E) 102,100
                                                 Committed Juvenile Population




space. Each of these variables represents                                        100,000
                                                                                                                                                             (D) 98,300
important considerations for policy and
practice. The number of youth referred to
court reflects the volume of delinquent                                           80,000
acts in the community, but it also reflects
                                                                                                                                                             (C) 75,100
the policies and priorities of the juvenile
                                                                                              Actual age-adjusted* committed
justice system, the availability of alterna-                                                                                                                  (B) 68,800
                                                                                                  population, 1991–1997
tives to secure confinement, and the range                                        60,000
of diversion options. The amount of time                                                                                                                     (A) 52,500
juveniles spend in residential facilities is a
function of offense seriousness, but it also
reflects policy decisions about the use of                                        40,000
secure confinement and the availability of
postrelease supervision. (For a discussion
of why length of stay is important and
                                                                                  20,000
how it is measured, see pages 12–13.)
                                                                                       1991            1993        1995      1997        1999        2001       2003
These relatively simple projection models
can also be used to consider different                                                                                           Year
policy and program choices and to simu-                    Assumptions:
late their effects. For example, suppose                   A. Admissions and length of stay (LOS) remain at 1997 levels.
juvenile justice officials know that the av-
                                                           B. LOS remains at 1997 levels; admissions projected based on 1993–97 trends.
erage length of stay for youth committed
for drug offenses will increase significantly              C. Admissions remain at 1997 levels; LOS projected based on 1993–97 trends.
because of plans to administer more drug                   D. Admissions and LOS projected based on 1993–97 trends.
treatment during confinement. Assume                       E. Admissions based on 1993–97 trends; LOS for drug offenders increases by 5 percent each
that the new drug treatment programs will                     year; LOS for all other offenders is projected based on 1993–97 trends.
increase the average length of stay for                    * For the definition of the “age-adjusted” juvenile commitment population, see table 1, second
drug offenders by 5 percent each year                      footnote.
between 1998 and 2002. For all other                       Source: Urban Institute analysis of OJJDP’s Census of Juveniles in Residential Placement
offenders (nondrug), length of stay will                   1997 data files, OJJDP’s Children In Custody census 1991, 1993, and 1995 data files, and
                                                           NCJJ’s National Juvenile Court Data Archive 1993 and 1997 data files.



                                                                                                  11
  Length of Stay: Why It Is Important and How It Is Measured
  Changes in the size of juvenile corrections populations can be                 able bias. As with the exit-cohort estimation technique, it
  understood in relation to the number of people who move into and               involves just one source of data (the current “stock”).
  out of facilities (or “flow”) and the length of time that they stay in
  facilities (length of stay). Length of stay is a critical ingredient in        In addition, average “days since admission” can significantly
                                                                                 overestimate length of stay because the current population
  projections of juvenile custody populations. A corrections or de-
  tention population can change dramatically if a facility’s length of           of any facility necessarily contains a disproportionately large
                                                                                 number of individuals who have had long stays.* If “days since
  stay begins to change, even if admissions are stable. Measuring
  length of stay, however, can be challenging. There are three com-              admission” is the only estimate possible with existing data, how-
                                                                                 ever, it can still be useful. The following is an example of a “days
  monly used methods of estimating length of stay.
                                                                                 since admission” estimate for a population containing five indi-
                                                                                 viduals. Using only today’s date and the admission dates for all
  Estimation Methods                                                             members of the population, it is possible to determine that the
  Exit Cohort
                                                                                 average length of stay for this population is 39 days.
  The most popular measure of length of stay is the average                      Calculating Average Length of Stay Using “Days
  amount of time spent in corrections by a group of youth released               Since Admission”
  during a given period of time. Known as an “exit cohort” esti-
                                                                                 Members
  mate, this technique for estimating length of stay is easy to cal-
                                                                                 of the           Admission                             Days Since
  culate and easy to interpret. However, it can underestimate the
                                                                                 Population         Date            Today’s Date        Admission
  length of time individuals actually spend in correctional facilities.
  By definition, exit cohorts contain a disproportionate number of               Person A         January 1            April 1                90
  individuals who had short stays.
                                                                                 Person B         February 1           April 1                59
  Calculating an exit-cohort estimate of length of stay is easy                  Person C         March 1              April 1                31
  once the necessary data are assembled. The following example
                                                                                 Person D         March 15             April 1                16
  shows the data for an exit cohort of five individuals released be-
  tween April 1 and June 1. By combining their admission dates                   Person E         March 31             April 1                 1
  and release dates and calculating each person’s length of stay,                Average                                                      39
  it is possible to determine that this cohort’s average length of
  stay was 87 days.
                                                                                 Stock/Flow Ratio
  Calculating Average Length of Stay With Data
                                                                                 A third method of estimating length of stay is to calculate a ratio of
  for an Exit Cohort
                                                                                 “stocks” and “flows,” where stock and flow are defined as follows:
  Cohort            Admission           Release        Length of Stay
                                                                                 Stock = the number of youth in a population on a given day (or
  Members             Date               Date            (in days)
                                                                                 some measure of average daily population).
  Person A         January 1             April 1              90
                                                                                 Flow = the number of youth released from the population over a
  Person B         January 1             April 10            100                 given period of time, usually monthly or annually. (If data on ac-
  Person C         February 1            April 23             82                 tual releases are not available, admissions data can be used to
                                                                                 estimate “flows,” but this assumes admissions and releases are
  Person D         February 1            May 15              104
                                                                                 in equilibrium over the time period of interest.)
  Person E         April 1               June 1               61
                                                                                 A stock/flow ratio can also be a biased estimator for length of
  Average                                                     87
                                                                                 stay if the size of the population or the release rate is changing
                                                                                 rapidly. The extent of the bias, however, may be less than that
  Days Since Admission                                                           of other estimates since stock/flow ratios involve information
                                                                                 from two sources (stock and flow). Calculating length-of-stay
  Another common measure of length of stay is the average num-
  ber of days that the current population of a detention or correc-
  tional facility has been in the facility as of a certain day. This         * Using “days since admission” to estimate a facility’s total length of stay
                                                                             would be similar to estimating the life expectancy of Americans by
  measure is easy to calculate, but it can also involve consider-
                                                                             calculating the average age of all people alive now.



follow the average annual trends seen dur-          and their effect on length of stay for drug           commitment populations, given varying
ing the 1993–97 period. Under these as-             offenders could increase the commitment               assumptions about future conditions. The
sumptions, the commitment population                population by almost 4,000 (the difference            value of these examples is limited by the
would nearly double from 53,000 in 1997 to          between projection D and projection E).               lack of more detailed data. For instance,
about 102,000 in 2002 (projection E). Thus,                                                               the models presented here divide the
the addition of drug treatment programs             These examples suggest how projection                 commitment population into only four
                                                    models could be used to anticipate future




                                                                            12
  Length of Stay—Continued
 estimates with stock/flow ratios can be fairly simple once the          the bias in the measures of length of stay. Once the potential
 appropriate information is available. The following two ex-             direction of the bias in each measure is assessed, the measures
 amples present length-of-stay estimates as stock/flow ratios.           can be compared and conclusions can be drawn about whether
                                                                         persons are spending more, less, or about the same amount of
 Example 1: Assume that a juvenile correctional facility had an
                                                                         time in custody.
 average daily population of 300 during the preceding year, and
 assume that 425 juveniles were released during the year. Using
 this information, an analyst could estimate the facility’s length of    Length of Stay in This Bulletin
 stay by dividing the stock (300) by the flow (425), which would         This Bulletin presents an analysis of the change in the juvenile
 suggest that juveniles stayed in the center for an average of           commitment population between 1993 and 1997, and it projects
 (300/425) years—or 259 days.                                            the commitment population for the year 2002. Both these analy-
                                                                         ses require measuring average length of stay. After considering
 Calculating Average Length of Stay as a Stock/Flow Ratio:               and computing several measures of length of stay, including “exit
 Example 1                                                               cohort” and “days since admission” measures, the authors de-
 Stock—average daily population in placement              300            cided to use stock/flow measures to provide the estimates of
                                                                         length of stay used in these analyses. The bias inherent in a
 Flow—juveniles released during previous year             425            stock/flow ratio is usually less than it would be for other length-
 Stock/flow ratio in years (300/425)                         0.71        of-stay measures (i.e., exit cohorts and days since admission),
                                                                         and using the stock/flow ratio provided a consistent and uniform
 Length of stay in days (0.71 X 365)                      259            method of measuring length of stay that was conducive to mea-
                                                                         suring the change in length of stay over the period.
 Example 2: Assume that a juvenile detention center has a popu-          A stock/flow measure for length of stay was calculated for 1993
 lation of 100 today, and assume that the director of the center         and 1997 using data on the number of out-of-home placements
 considers today’s population typical. If 85 juveniles were re-          taken from NCJJ’s National Juvenile Court Data Archive (NJCDA)
 leased from the center during the previous month, a forecaster          and data on the number of youth in corrections taken from
 could estimate the center’s length of stay by dividing the stock        OJJDP’s Children in Custody (CIC) census and its Census of
 (100) by the flow (85), which would suggest that juveniles stayed       Juveniles in Residential Placement (CJRP). The use of admis-
 in the center for an average of (100/85) months—or 36 days.             sions rather than releases is required because national-level
                                                                         data on releases are not available. This choice assumes that
 Calculating Average Length of Stay as a Stock/Flow Ratio:
                                                                         releases are estimated by admissions. Under this assumption, if
 Example 2
                                                                         admissions are greater than releases (likely during the study
 Stock—average daily population in placement                100          period), then a stock/flow ratio may underestimate length of stay.
                                                                         Conversely, if admissions are less than releases (unlikely during
 Flow—juveniles released during previous month                85         the study period), then a stock/flow ratio would overestimate
 Stock/flow ratio in months (100/85)                            1.18     length of stay. The table below displays the stock/flow ratios
                                                                         used in the analyses presented in this Bulletin.
 Length of stay in days (1.18 X 30.4†)                        36
                                                                                            1993 CIC                  1997 CJRP
                                                                                          Stock/NJCDA                Stock/NJCDA
 Estimation Bias                                                         Offense        Flow Ratio (days)          Flow Ratio (days)
 As any measure of length of stay is likely to involve bias, correc-     Total                  96                        109
 tions planners may want to use several estimators to understand
 how the length of time served is changing. By understanding the         Person                162                        180
 conditions that characterize the corrections system—such as
                                                                         Property               89                        104
 increasing admissions and slowing rates of release—the user
 of length-of-stay information can assess the likely direction of        Drugs                 148                        113
                                                                         Public order           22                          49
 † Number of days in the average month, 365/12.




categories of offenders—person, prop-             wish to apply projection models in actual      flight risks, those who have school prob-
erty, drug, and public order. Obviously,          decisionmaking situations, they would          lems, those with educational deficits, etc.
projections would be even more useful if          prefer even more data. In addition to di-      Ideally, projection models should be cal-
offenses could be divided into additional         viding the juvenile population by offense,     culated for any categories or factors that
categories (e.g., felony or misdemeanor,          projection models can sometimes be cal-        may be involved in actual agency deci-
weapon or weaponless, drug possession             culated separately for juveniles who are       sions about the use of juvenile bedspace
or drug sales). Moreover, when agencies           drug dependent, those who are known            in detention or correctional facilities.



                                                                        13
Population Projections                            models allow decisionmakers to consider a       mary of commonly used projection mod-
                                                  wide range of policy choices and to incor-      els follows on page 15.) If used in this
in Practice                                       porate those choices into a series of differ-   way, population projections can be flex-
The previous discussion demonstrates              ent models so that their effect on future       ible tools for understanding the ramifica-
how assumptions about future conditions           populations can be seen. (A brief history       tions of various policy choices and the
are critical to the results of projection         of corrections population projection            use of confinement resources. Projection
models. The most effective projection             methods is presented below and a sum-           models, however, should not be offered


  A Brief History of Corrections Population Projection Methods
  Beginning in the early 1970’s, correc-          In addition, statistical models are effective   Microsimulation models project prison
  tions researchers began to develop in-          only when data are available for extended       populations by simulating what happens
  creasingly sophisticated methods for            periods, and they can be difficult to inter-    to individual offenders as they are pro-
  projecting adult prison populations. Their      pret for nontechnical audiences.                cessed by the justice system and enter
  methods drew largely from the fields of                                                         and leave prison. Early microsimulation
                                                  In 1980, Alfred Blumstein and his col-          models began by estimating the length of
  demography and operations research.
                                                  leagues continued the development of
  Since the 1970’s, population projection                                                         time individual offenders were likely to
                                                  mathematical flow models by making two          remain in prison. For each prison admis-
  models and the data available for those
                                                  enhancements to the Stollmack model
  models have improved considerably. The                                                          sion, a path (or “trace vector”) is mapped.
                                                  (Blumstein, Cohen, and Miller, 1980). First,    Future prison populations are projected
  fundamentals of population projections,
                                                  they disaggregated population projections
  however, are still based on the work of                                                         by adding together the number of indi-
                                                  by racial and crime categories. Second,         viduals remaining in prison at any given
  a few original innovators.
                                                  instead of assuming a constant rate of ad-
                                                                                                  point in the future. The California Depart-
  In 1973, Stephen Stollmack published            missions into the population, their model       ment of Corrections developed one of
  one of the first “mathematical flow” mod-       projected admissions as age-specific pro-
                                                                                                  the first functional microsimulation mod-
  els for projecting prison populations.          portions of the general population. They        els in the early 1970’s (Chaiken and
  The model used an input-output analy-           developed these proportions with census
                                                                                                  Carlson, 1988).
  sis of the corrections system. It incor-        projections and historical data on prison
  porated data about how offenders                admissions. Their innovation acknowledged       In the early 1980’s, the National Council
  “flowed” through the stages of the jus-         that rates of crime, arrest, and incarcera-     on Crime and Delinquency drew from the
  tice process—for example, from arrest           tion varied among groups in the general         experiences of California when it devel-
  to indictment, conviction, and incarcera-       population. Population projections were         oped its “Prophet” model (National Coun-
  tion. Prison populations were projected         calculated as a weighted sum of the sepa-       cil on Crime and Delinquency, n.d.). The
  by relating flows to “stocks” (or the start-    rate projections for each subpopulation.        Prophet model was constructed on the
  ing point of a prison population) and by                                                        concept of “ID groups”—subpopulations
                                                  Arnold Barnett (1987) introduced another
  incorporating information on the aver-                                                          of offenders categorized according to how
                                                  refinement to mathematical flow models          they were likely to be handled in the jus-
  age length of time individuals stay in
                                                  based on the concept of “criminal careers.”
  prison. The model even allowed for lim-                                                         tice system. Each group could be mod-
                                                  Barnett’s model began with age-specific         eled through various decision points in
  ited evaluations of policy changes (for
                                                  probabilities that nonincarcerated offenders
  example, the impact of policies that                                                            the criminal justice system, and lengths
                                                  are actively involved in crime. His model       of stay were estimated using sentencing
  change length of stay can be built into
                                                  estimated the incarceration rate for offend-
  the model and their impacts can be as-                                                          variables or data on time served by previ-
                                                  ers based on several factors—age, criminal      ous cohorts of released offenders. Incar-
  sessed by seeing how the prison popu-
                                                  activity, and the expected rate of desis-
  lation is affected).                                                                            cerated populations were projected by
                                                  tance. The probability of criminal activity     estimating the number of offenders in
  Stollmack’s model took population pro-          could be revised within the model to ac-
                                                                                                  each ID group who were expected to be
  jections beyond traditional statistical         count for policy changes, and the impact        in prison at certain points in the future.
  models (e.g., time series and regres-           of these changes could be factored directly
  sion). Statistical models projected future      into projections of prison populations.         Unfortunately, many State and local agen-
  populations by linear extrapolation of                                                          cies are still unable to produce the de-
                                                  While Blumstein and his colleagues and
  trends in prior populations. Statistical                                                        tailed data necessary to make full use of
                                                  Barnett were improving Stollmack’s math-        microsimulation models. In practice, most
  models continue to be used today be-
                                                  ematical flow model, other researchers were
  cause they allow forecasters to make                                                            jurisdictions continue to use grouped data
                                                  developing an entirely different approach       rather than individual-level data in their
  projections without having to assemble
                                                  to population projections. This second ap-
  a great deal of data about case process-                                                        population projections. Whenever grouped
                                                  proach would become known as “micro-            data are used, microsimulation models
  ing. With statistical models, however,
                                                  simulation.” By the end of the 1990’s, 24
  forecasters cannot disaggregate projec-                                                         function essentially as disaggregated flow
                                                  States and the Federal Bureau of Prisons        models.
  tions for subpopulations, nor can they
                                                  were using some form of microsimulation
  analyze the impact of policy changes
                                                  to project prison populations (Sabol, 1999).
  that affect only certain types of offenders.

 Note: Much of this history is drawn from Sabol (1999).




                                                                       14
to policymakers as a simplistic mecha-          significant expansions in their data col-            should invest in an extended process of
nism for predicting future corrections          lection and analysis capabilities, it is un-         “forecasting.”
populations.                                    likely that any projection model will ever
                                                represent the true diversity of the juve-            Forecasting Rather Than
Because projection models are unable to         nile population. For this reason, juvenile
account for all of the details involved in                                                           Predicting
                                                justice agencies should resist the temp-
the juvenile justice process, they will         tation to rely on any single prediction of           Forecasting is different from predicting,
never be foolproof. Moreover, until State                                                            although both strategies involve statistical
                                                future demand for space. Instead, they
and local agencies are able to support                                                               projections of corrections populations.


  Models Commonly Used To Project Corrections Populations
  Projecting corrections populations is often incorrectly under-             tion that will hold true only if current assumptions about the fac-
  stood as an effort to “get the right number.” This assumes that a          tors that generated past populations persist into the future.
  projection is inferior if it produces a number that turns out to be        A comprehensive forecasting effort should include not only
  different from actual need or if a projection becomes irrelevant           population projections but also policy debates and analyses to
  after a change in policy. It is more appropriate to view projec-           understand why actual populations depart from projections and
  tions as conditional statements of a future corrections popula-            to demonstrate the role of policy in shaping demands for space.

    Type of Model                         Method or Approach                                                 Comments

    Microsimulation         x Projects the movement of individual entities              x Offers the greatest flexibility/power in projecting
                              through the justice system using detailed infor-            populations under various policy assumptions.
                              mation about real individuals who have gone
                              through the system or are still in process.               x Requires extensive data about individual
                                                                                          offenders.
                            x Permits users to aggregate information at the
                              end of a simulation into whatever categories              x Most State and local jurisdictions are not able
                              are needed.                                                 to meet the data requirements.

                                                                                        x For national-level projections, data requirements
                                                                                          for microsimulation will likely never be met.

    Disaggregated           x Uses rates of flow between the stages of the              x Generates projections based on the movement
    flow                      justice system (e.g., odds of adjudication after            of groups through the justice system.
                              arrest, odds of incarceration after adjudication).
                                                                                        x Next to microsimulation, offers the most flex-
                            x Rates can be entered and then altered for                   ibility for anticipating future conditions.
                              various subpopulations for repeated projec-
                              tions over time.                                          x Requires grouped data only.

    Statistical             Uses methods such as time series or multiple                x Requires less data but does not provide much
                            regression to project populations based on                    flexibility for modeling future policy changes.
                            changes in other, related variables.
                                                                                        x Generates projections based on past values of
                                                                                          the variable to be projected and their relation-
                                                                                          ship to other factors.

                                                                                        x May require the values of independent or
                                                                                          causal variables to be projected as well.

    Mathematical            May involve various methods, ranging from                   x Requires minimal data but is very inflexible.
                            simple growth-rate projections to more sophisti-
                            cated stochastic models.                                    x Projections are generated by adding a con-
                                                                                          stant to existing populations or by multiplying
                                                                                          populations by calculated growth rates.

                                                                                        x Assumes future conditions will be the same as
                                                                                          past conditions.

                                                                                        x May include parameters that relate inflow to out-
                                                                                          flow or that model length of stay in corrections.




                                                                        15
Forecasting Juvenile                              Differences Between Predicting and Forecasting
Corrections Populations                                                         Predicting                        Forecasting
in Oregon
                                                  Focus                       Future                          Recent past
The Oregon Youth Authority obtains                Goal                        Accurately predict              Examine recent develop-
twice-yearly forecasts of the number                                          the future                      ments and their relevance
of young offenders likely to be in its                                                                        for the future
“close custody” programs 10 years into
the future. (Close custody refers to              Methods                     Statistical projections         Statistical projections,
youth housed in the State’s MacLaren                                                                          policy discussions,
and Hillcrest facilities and also those in                                                                    program reviews
“accountability camps,” “work study
                                                  Personnel Involved          Analysts                        Policymakers, admini-
camps,” and Oregon’s Juvenile Intake
                                                                                                              strators, practitioners,
Center.) Forecasts are generated by
                                                                                                              analysts
Oregon’s Office of Economic Analysis
using models developed by the office              Frequency                   As needed                       Regularly
and overseen by an interdisciplinary
advisory committee. Members of the                Definition of Success       Accuracy                        Utility/learning
committee include researchers from
a local university, court and probation
officials, and the Director of the              Forecasting relies on reflection instead of      No single projection exercise should
Oregon Youth Authority.                         speculation. In a prediction context, re-        drive policy and budgetary decisions.
                                                searchers focus on the future. They use          Every projection should be used in con-
Each forecast incorporates the most             data about the past to speculate about the       junction with policy debates about the
recent data on intake trends, arrest            future, and they encourage policymakers          type of programs a jurisdiction wishes to
trends, and future population growth            to act on their statistical vision of the fu-    support. Decisionmakers can use a fore-
for Oregon youth ages 12 through 17.            ture. In a forecasting context, researchers      casting process to reflect on current poli-
Separate models are used to forecast            focus on the recent past. They use data to       cies and practices and to ask critical
important subpopulations within the             understand how the recent past turned            questions about their use of bedspace: If
juvenile offender population, including         out to be different from previous expecta-       current trends continue, which type of
youth affected by Oregon’s “Ballot              tions. By identifying and examining these        offenders will be committed to secure
Measure 11,” which automatically                differences, policymakers and other pro-         confinement and which will be placed in
transfers certain categories of offend-         fessionals increase their understanding of       community-based programs? What type
ers to the criminal court.                      the factors that are likely to influence fu-     of offenders will stay the longest in se-
The forecasts are provided to policy-           ture trends, but they do not place undue         cure facilities? Which facilities will see
makers and other officials in the State         faith in anyone’s ability to predict those       the largest increases in daily populations
to foster discussions about recent              trends accurately.                               or length of stay? Which areas of the
trends and their effect on future correc-                                                        State will experience the greatest
                                                A forecasting approach also encourages           changes in expected demand? Projec-
tions populations. The Office of Eco-           decisionmakers to review their assump-
nomic Analysis advises officials that                                                            tions of future custody populations
                                                tions about their own policies and prac-         can be powerful learning tools that
each “forecast is not what the popula-          tices on a regular basis. Some agencies
tion will be, but what the population                                                            serve the twin goals of making com-
                                                may engage in a forecasting process on           munities more secure and providing
would be if current practices and poli-         an annual or even semiannual schedule.
cies were applied to future conditions”                                                          appropriate treatment programs for
                                                They conduct repeated projections of             youth.
(Oregon Youth Authority Close Custody           their corrections populations and com-
Population Forecast: Biennial Review of         pare actual developments with their
Methodology, page 2).                           previous expectations of demand for              Forecasting and the
                                                bedspace. Administrators and policy-             Policy Process
Source: Oregon Youth Authority Close            makers use the occasion of each forecast-        The juvenile justice process has many
Custody Population Forecast (April 2000),       ing exercise to review their assumptions         unique features that need to be ac-
a biennial series, and Oregon Youth Authority   about their system and how it uses               counted for in projection methodologies.
Close Custody Population Forecast: Biennial
Review of Methodology (June 1998). Salem,       bedspace. In such an environment,                These features include a wide use of di-
OR: Oregon Office of Economic Analysis.         population projections can be used to            version, great discretion at all levels, and
Also available on the Internet at               encourage sound policy and practice              the juvenile court’s ability to base dispo-
www.oea.das.state.or.us/oya/oya.htm.            decisions. (See “Forecasting Juvenile Cor-       sitions on not only the public safety but
                                                rections Populations in Oregon” on this          also on the best interests of the juvenile.
                                                page for a description of one agency’s ap-       Because juvenile court dispositions are
                                                proach to integrating forecasts into its         sometimes for indeterminate periods of
                                                policy process.)                                 time, lengths of stay are often linked not
                                                                                                 only to the severity of the offense but



                                                                     16
  Methodology
  Decomposition Methods                                                     changes in each individual component of change as measured
  A statistical flow model is used in this analysis to decompose            in the above model. Thus, the difference in the population is a
  changes in the national juvenile commitment population be-                “weighted sum” of differences in each component, where the
  tween 1993 and 1997. The model segments the overall change                weights equal the offense-specific contribution to change in the
  in the commitment population into offense-specific groups (per-           population. The decomposition of change is applied separately
  son, property, drug, and public order). Within each group, the            to each offense group, and each of the offense-specific changes
  model decomposes the overall change in the commitment popu-               in the juvenile commitment population can be summed to obtain
  lation into the portions of total change that can be attributed to        the total change in the population between 1993 and 1997.
  the following factors:
                                                                            Projection Calculation
  x Changes in the number of juvenile court referrals.
                                                                            Using data for the 1993–97 period, a mathematical flow model is
  x Changes in the number of referred cases that result in                  used to project the juvenile commitment population for the years
    adjudication.                                                           1998 through 2002. The model follows the approach developed
                                                                            by Stollmack (1973) to project prison populations. The analysis
  x Changes in the number of adjudicated cases that result
                                                                            uses the following equation to project the juvenile committed
    in residential placement.
                                                                            population for each year, from 1998 to 2002:
  x Expected length of stay in residential placement (using
                                                                            P(t ) = A(t ) x LOS(t ) + [P(t–1) – (A(t ) x LOS(t ))] x exp[–1/LOS(t )]
    a stock/flow estimate of length of stay).
                                                                            Where each element is defined as follows:
  The offense-specific changes in these components of growth
  are then aggregated to obtain the total change in the juvenile            P(t–1)     =   the population in the previous year (t–1).
  commitment population over the period of analysis.
                                                                               A(t )   =   admissions or commitments to residential place-
  The population change model used in this Bulletin follows the                            ment during the year.
  approach of Abrahamse’s (1997) method for assessing change
  in prison populations. The number of juveniles committed to               LOS(t ) =      the estimated length of stay in commitment.
  residential placements at the end of a year is defined as follows:               t   =   the time unit for flows (in this example, years).
         POPULATION = REFERRALS x ADJUDICATION                              This model requires three data inputs for each time period: the
             x PLACEMENT x LENGTH OF STAY                                   starting population, which is the population from the previous
  Where each element is defined as follows:                                 time period [P(t–1)]; admissions during time t ; and length of
                                                                            stay. The projection scenarios described in this Bulletin use
      POPULATION       =    the juvenile population committed to            the 1997 juvenile commitment population as the initial starting
                            residential placement facilities.               population and assume that admissions either remained at
                                                                            1997 levels throughout the 1998–2002 period or that they in-
       REFERRALS       =    the total number of delinquency cases
                                                                            creased each year based on applying the average annual
                            referred to the juvenile court system.
                                                                            changes observed from 1993 to 1997. Similarly, average length
    ADJUDICATION       =    the proportion of referred cases that           of stay is either assumed to remain at 1997 levels or projected
                            results in adjudication.                        for each year based on the average annual change observed
                                                                            from 1993 to 1997.
       PLACEMENT       =    the proportion of adjudicated cases
                            that results in commitment to residen-          As with the decomposition model, the projection models pre-
                            tial placement facilities.                      sented in this Bulletin were apportioned into offense-specific
                                                                            components (person, property, drug, and public order) and then
  LENGTH OF STAY =          the expected length of stay, estimated          summed to obtain the total populations projected for each year
                            by a “stock/flow” ratio (see discussion         from 1998 to 2002. Since data on the number of committed
                            on pages 12–13).                                youth released from residential placement were not available for
  The amount of change in the juvenile commitment population                all years in this analysis, the model presented in this Bulletin
  between 1993 and 1997 is a function of the offense-specific               must assume that admissions and releases were in equilibrium.



also to a youth’s progress in treatment        stand that no projection methodology                   tion model and consider its value for
programs and the availability of space.        will ever be able to model the complexity              policy and practice. However simple it
As a result, juvenile detention and cor-       of the decisionmaking processes that                   may appear at first, estimating a juris-
rections systems have much less stable         lead juvenile offenders to be placed in                diction’s future need for detention and
information on which to build forecasts        secure facilities or that determine how                corrections space requires an extensive
than criminal justice agencies.                long juveniles will stay in those facilities.          examination of the justice system and of
                                               It will always be necessary for decision-              the processes used to select juvenile
Researchers must encourage policy-             makers to review the results of a projec-              offenders for placement.
makers and administrators to under-



                                                                       17
An effective forecasting process should       Conclusion                                      regular basis and exposes each set of
take into account the important role                                                          projections to the scrutiny of a broad
played by each jurisdiction’s policy pref-    Efforts to anticipate future space needs        range of audiences and stakeholders.
erences and professional practices. Fore-     in juvenile detention and juvenile correc-
casting should include at least three gen-    tions facilities should involve more than
eral areas of activity:                       an occasional analysis of juvenile arrest       Endnotes
                                              trends. Ideally, juvenile justice decision-
                                                                                              1. These numbers represent different
x First, decisionmakers should have           makers should anticipate future demands         units of count, and this analysis should
  regular access to extensive data about      for space by engaging in a population
                                                                                              not be interpreted as suggesting that
  trends in juvenile crime and juvenile       forecasting process on an annual or semi-       exactly 62 percent of all arrested youth
  justice processing within their jurisdic-   annual basis. Forecasting involves statisti-
                                                                                              were referred to juvenile courts in 1997.
  tions, and they should use that infor-      cal predictions (or projections) of future      Changes in the relationship between juve-
  mation to project the size of future de-    corrections populations, but the results
                                                                                              nile arrests and juvenile court cases, how-
  tention and corrections populations.        of such projections serve as the begin-         ever, do indicate law enforcement’s shift-
x Second, they should develop a thor-         ning of an agency’s decisionmaking pro-
                                                                                              ing emphasis on court referral.
  ough understanding of their jurisdic-       cess rather than the end. Forecasting en-
  tion’s policies and practices regarding     courages policymakers and practitioners         2. This example is intended as a demon-
  the use of secure confinement for ju-       to use statistical projections to reflect on    stration of projection methodology and
  venile offenders, including how the         recent trends and discuss their expecta-        not an analysis of national custody popu-
  diversity and depth of juvenile justice     tions of the future in light of those trends.   lations that could be used to formulate
  resources are related to the need for       The accuracy of their expectations can          State or Federal policy. For this reason,
  secure space.                               then be reviewed during the next fore-          all data, including population counts, are
                                              casting session. Over time, a forecasting       rounded.
x Third, they should host a rotating se-      process helps decisionmakers to antici-
  ries of strategy meetings with a variety    pate the consequences of policies and           3. The juvenile custody population num-
  of audiences from the juvenile justice                                                      bers in table 1 are drawn from the Census
                                              practices regarding secure bedspace with-
  system and the larger community.            out undue reliance on statistical analysis.     of Juveniles in Residential Placement
  These meetings should focus on the                                                          (CJRP) in 1997 and from the Census of
  relationships among the availability of     No projection method is infallible, but         Public and Private Juvenile Detention,
  juvenile justice program resources,         juvenile justice officials must choose          Correctional, and Shelter Facilities, also
  recent trends in the use of those re-       some method for planning for future             known as the Children in Custody (CIC)
  sources, and projections of future          space needs. Without careful projections        census, in the years prior to 1997. CJRP
  confinement populations.                    of the likely demand for detention and          differs fundamentally from CIC, which col-
                                              corrections space, policymakers and ad-         lected aggregate data on juveniles held in
The validity of any projection model
                                              ministrators make important decisions           each facility. CJRP collects individual data
rests on the reasonableness of its as-
                                              about the need for additional facilities        on each juvenile held in each residential
sumptions and the persistence of these
                                              based primarily on the immediate pres-          facility in the census. Since there was a
assumptions into the future. When pro-
                                              sures of crowding. However, crowding            change in data collection instruments, it
jections fail to anticipate future condi-
                                              is an indicator of past demand. Budget-         is difficult to determine how much of the
tions, forecasters should seek to explain
                                              ing and policymaking must prepare an            increase in the number of delinquents in
why actual populations differ from pro-
                                              agency for the future. Making important         custody is real and how much is due to
jected populations. Decisionmakers then
                                              decisions without attempting to project         the change in methods. According to
have the opportunity to learn about the
                                              future conditions can leave the juvenile        OJJDP (see Snyder and Sickmund, 1999),
effects of practice and policy actions
                                              justice system unprepared and lead to           the “roster” format of the CJRP data,
that were not included in the projection.
                                              inefficient uses of costly resources.           along with electronic reporting, may have
The success of a forecasting process is                                                       facilitated a more complete accounting of
                                              Projecting future demand for bedspace           juveniles in facilities. In the years when
not determined by its predictive accu-
                                              will always be challenging because the
racy. A projection that turns out to be                                                       CIC was used, there were many private
                                              policy environment in juvenile justice is       facilities that did not report juveniles
wrong (or one that produces population
                                              highly dynamic. As Allen R. Beck once
estimates that deviate from actual future                                                     in custody. It is therefore likely that the
                                              observed: “Using the past to ‘see’ the          reported number of juveniles in private
populations) is not necessarily an invalid
                                              future is like driving a car by looking into
projection. An invalid projection is one                                                      facilities is understated. The population
                                              the rear view mirror. As long as the road       counts presented here do not match
in which the differences between a pro-
                                              is straight or curving in wide arcs, the
jected population and the actual popula-                                                      the data reported in other analyses of
                                              driver can stay on the road by looking          OJJDP’s CJRP data due to the various
tion cannot be explained. A projection
                                              backward. However, if a sharp turn oc-
that turns out to be inaccurate as a pre-                                                     adjustments in this analysis.
                                              curs or a bridge is out, the driver will
diction may still be a useful projection if
                                              crash” (Beck, 1998). The policy environ-        4. Adjustments were based on the as-
analysts are able to explain which criti-
                                              ment in juvenile justice has taken many         sumption that the 1997 population repre-
cal assumptions were violated and what
                                              sharp turns in recent decades. Agencies         sents an accurate count of juveniles in
impact these violations had on correc-
                                              can improve the usefulness of population        custody in both private and public facili-
tions populations.
                                              projections by investing in a forecasting       ties. The ratio of the private to public
                                              process that generates projections on a         populations in 1997 was applied to the



                                                                   18
1993 and 1995 reported counts of juve-          Chaiken, J., and Carlson, K.E. 1988. Review   of Justice, Office of Justice Programs,
niles in public facilities to adjust the num-   and Evaluation of the California              Office of Juvenile Justice and Delin-
ber of youth in private facilities in those     Department of Corrections’ Institution        quency Prevention.
years.                                          and Parole Population Projections. Sacra-
                                                mento, CA: California Department of           Stollmack, S. 1973. Predicting inmate
5. The number of “admissions” into resi-                                                      populations from arrest, court disposi-
                                                Corrections, Offender Information Ser-
dential facilities is required to compute       vices Branch.                                 tion, and recidivism rates. Journal of
the relative rate of placement for any                                                        Research in Crime and Delinquency
given year. A count of admissions is also       National Council on Crime and Delin-          10(1):141–162.
essential input for projecting future juve-     quency. n.d. Introduction to the NCCD
nile commitment populations. Data on            Prophet Simulation Model: An Interactive
                                                                                              This Bulletin was prepared under grant
true admissions, however, are not avail-        Microcomputer Simulation System. San
                                                                                              number 98–JB–VX–K004 from the Office of
able from any national data collection          Francisco, CA: National Council on Crime
                                                                                              Juvenile Justice and Delinquency Prevention,
program (e.g., the National Juvenile Court      and Delinquency.
                                                                                              U.S. Department of Justice.
Data Archive, the Census of Juveniles in
Residential Placement, or the Children in       Sabol, W.J. 1999 (May). Prison popula-
                                                                                              Points of view or opinions expressed in this
                                                tion projection and forecasting: manag-
Custody census). The National Juvenile                                                        document are those of the authors and do not
Court Data Archive, however, can provide        ing capacity. Unpublished report. Pre-
                                                                                              necessarily represent the official position or
                                                pared for the Bureau of Justice Statistics,
data on the number of adjudicated juve-                                                       policies of OJJDP or the U.S. Department of
nile court cases resulting in commitment        Corrections Program Office, and the Na-
                                                                                              Justice.
                                                tional Institute of Justice, Washington,
to residential placement during each year
of the analysis. These data are used as a       DC. NCJ 172844.
                                                                                               The Office of Juvenile Justice and Delin-
proxy for the number of “admissions” into       Snyder, H. 1999. Juvenile Arrests 1998.        quency Prevention is a component of the Of-
residential placement.                          Washington, DC: U.S. Department of Justice,    fice of Justice Programs, which also includes
                                                Office of Justice Programs, Office of Juve-    the Bureau of Justice Assistance, the Bureau
6. Transition probabilities were calculated
for 1993 and 1997 on an offense-specific        nile Justice and Delinquency Prevention.       of Justice Statistics, the National Institute of
basis. The overall change in the commit-        Snyder, H., and Sickmund, M. 1999. Juve-       Justice, and the Office for Victims of Crime.
ment population between 1993 and 1997           nile Offenders and Victims: 1999 National
was then decomposed into the changes in         Report. Washington, DC: U.S. Department
these transitions from stage to stage dur-
ing the period.

                                                  Acknowledgments
References
                                                  This Bulletin was written by Jeffrey Butts, Ph.D., Director of the Assessment of
Abrahamse, A. 1997. The impact of de-
                                                  Space Needs in Juvenile Detention and Corrections project at The Urban Institute,
mography and criminal justice process-
                                                  and William Adams, Research Associate with the project. The project is housed
ing on prison population size. From the
                                                  within The Urban Institute’s Justice Policy Center, directed by Dr. Adele Harrell.
National Workshop on Prison Population
                                                  Development of the Bulletin benefited from significant contributions by Ojmarrh
Projection and Forecasting: Managing
                                                  Mitchell, Research Associate with The Urban Institute; Dr. William Sabol, formerly
Capacity. Washington, DC: National Insti-
                                                  of The Urban Institute and now Associate Director of the Center on Urban Poverty
tute of Justice, Bureau of Justice Statis-
                                                  and Social Change at Case Western Reserve University; Joseph Moone, Program
tics, and Corrections Program Office.
                                                  Specialist in OJJDP’s Research and Program Development Division; and
Barnett, A. 1987. Prison populations:             Dr. Helen Marieskind, a Writer/Editor in OJJDP’s Information Dissemination Unit.
A projection model. Operations Research           The authors are also grateful for comments and criticisms provided by Dr. Howard
35(1):18–34.                                      Snyder and Dr. Melissa Sickmund of the National Center for Juvenile Justice.
Beck, A.R. 1998 (August). Forecasting: Fic-       Both OJJDP and The Urban Institute gratefully acknowledge the efforts of the
tion and utility in jail construction plan-       State and local officials who assisted in the project. Their participation helped to
ning. Correctional Building News. Available       make this Bulletin possible. In particular, senior officials from the State-level
online at www.justiceconcepts.com.                juvenile corrections agencies in Alaska, California, Kentucky, Louisiana, Montana,
                                                  New Hampshire, South Carolina, West Virginia, and Wisconsin provided critical
Blumstein, A., Cohen, J., and Miller, H.          comments and insight.
1980. Demographically disaggregated
projections of prison populations. Jour-
nal of Criminal Justice 8(1):1–25.




                                                                    19
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                     Bulletin                              NCJ 185234

				
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Description: OJJDP,�March 2001,�NCJ 185234. (20 pages).