Implication by Z7CO91g3

VIEWS: 28 PAGES: 51

									Centre for Market and
Public Organisation




  Can pay regulation kill? Panel data evidence on
      the effect of labor markets on hospital
                    performance
                        Emma Hall, Carol Propper John Van Reenen
                                       Feb 2008




                                                                   1
                    Motivation
• Unintended consequences of wage regulation
   – Pay setting (e.g. public sector) often has
     “geographical equity” despite different local labor
     markets. Implies problems of labour supply - and
     poor performance - when outside labour mkts strong
• How do labour markets affect firm performance?
   – Hard to identify as wages reflect equilibrium
     outcomes of demand and supply shocks.
   – In our design, pay regulation help identification
• Policy issue in hospital performance
   – What are causes of large performance variation (note
     also large productivity dispersion in other industries)
                                                           2
                    Our Design
• Wages for nurses (and doctors) in UK National Health
  Service centrally set by National Pay Review Body.
  NPRB “Mandates” wage rates for doctors and nurses by
  grade. Uprated each year.
• Very little local variation in regulated pay despite
  substantial local variation in total private sector
   – E.g. 65% private sector pay gap between North-East
     England and Inner London but only 11% in NPRB
     regulated pay
   – Use exogenous variation in “outside wage” and
     examine impact on hospital outcomes (quality, prody)
• Institutional setting one in which selection of patients to
  hospitals is limited

                                                                3
                Our Results
• Main Finding: Hospitals in high outside wage
  areas have lower hospital quality (higher AMI
  death rates) and lower output per head.
• Not result of general UK labour market
  conditions
  – Placebo experiments on similar sectors: no evidence
    of negative effect of outside wages on productivity
• One mechanism: greater reliance on lower
  quality temporary/agency staff.


                                                          4
Geographical variation in:


    Outside wages            Agency nurses   In-hosp AMI
                                             deaths




                                                           5
OUTLINE



1. Models: What is the effect of pay regulation?

2. Empirical models


3. Data


4. Results


5. Conclusions

                                                   6
     1. Effects of high outside wage
        relative to regulated wage
• Employers
   – try to circumvent by “over-promoting” (grade drift) and increasing
     non-wage benefits. Limited by regulation/union enforcement
   – Substitution to other factors: health care assistants, maybe
     capital. But limited due to nature of needed expertise.
   – Substitute temporary agency staff. Lower job-specific human
     capital so less productive/lower quality (cf Autor & Houseman,
     2006)
• Employees
   – Lower participation, higher vacancies for permanent staff
   – More likely to become agency staff.
   – Permanent staff also less motivated, lower relative quality
     compared to low outside wage areas

   Implication: Worse hospital performance in high outside wage areas


                                                                      7
                 Implications
• In high outside wage areas
  – Problems of labour supply for permanent staff
     • higher vacancies
     • lower participation in nursing
     • Greater reliance on agency nurses
  – Worse health outcomes
     • Lower quality (AMI death rate)
     • Lower productivity
  – See this in raw data at regional level
                                                8
                2. Empirical Models
1. Hospital quality equation

d it  1d SitPHYS   2d SitNURSES   d wit   d wit   d zit  id  ri d   id  it
                                                     O          d                         d




For hospital i in year t:
d = 30 day death rate from emergency AMI admission for 55+ year
olds
SPHYS = share of clinical workforce who are physicians
SNURSES= share of clinical workforce who are nurses (and AHPs)
(base group is health care assistants)
wO = ln(outside wage)
Z = controls for casemix, area mortality rates, hospital size,
teaching status
w = ln(inside wage)
η = hospital dummies
τ = time dummies, r=regional dummies                                                          9
  2. Hospital productivity equation

ln(Y / L) it  1 SitPHYS   2 SitNURSES   wit   wit  zit  i  ri   i  it
                                                       O



    Ln(Y/L) = ln(Finished Consultant Episodes per clinical worker)
    SPHYS = share of clinical workforce who are physicians
    SNURSES= share of clinical workforce who are nurses (and AHPs)
    (base group is health care assistants)
    wO = ln(outside wage)
    Z = controls for casemix, area mortality rates, hospital size,
    teaching status
    w = ln(inside wage)
    r = regional dummies
    τ = time dummies
    η = hospital dummies

                                                                                         10
3. Placebo productivity equation

   ln( R / L) it  1 Sit
                        QUAL
                               wit   wit  zit  i  ri   i   it
                                          O



  Ln(R/L) = ln(revenues/worker)
  SQUAL = share of workforce who are qualified (nursing homes: with
  nursing quals; ln (cap/labor) ratio other industries)
  wO = ln(outside wage)
  Z = total staffing (+ gender mix, age of staff for nursing homes)
  w = ln(inside wage)
  r = regional effects
  τ = time dummies
  η = firm fixed effect
  Run for 42 industries + nursing homes


                                                                             11
                   Issues
• Unobserved heterogeneity: OLS, long
  differences and “System GMM”
• Endogeneity of wages and shares:
  – Outside wage: hospitals are a small % of local
    labor market
  – Skill shares: GMM-SYS (Blundell-Bond,2000;
    Bond and Soderbom, 2006)
• Standard errors allow for heteroscedacity,
  autocorrelation and clustering by region
                                                 12
                        Issues
• Endogeneity of patient quality
   – Selection of hospitals
   – Association of illhealth and economic activity
• Hospital selection limited by inst. structure
   – AMI patients sent to nearest hosp.
   – Hospitals not monitored on quality; in theory financial
     incentives exist but no systems to implement
• Upswings less associated with increase in hrs
  (due to higher labor protection); also undertake
  extensive checks to ensure no rel. between
  community health and ‘good times’
                                                           13
                   3. Data
• Hospital level panel data
• 3 groups of clinical workers: Physicians, nurses
  (AHPs) and Health Care Assistants. Total
  employment. From Medical Workforce Statistics
• Agency staff – hospital financial returns
• Hospital quality: 30 day in-hospital death rates
  for Emergency admissions for Acute Myocardial
  Infarction (AMI) for over 55 year olds. From HES
  (Hospital Episode Statistics).
• Productivity: Finished Consultant Episodes
  (HES) per worker

                                                 14
                  Wage Data
• Outside wage
  – New Earnings Survey (NES) 1% sample of all
    workers
  – Use travel to work area (78 in England)
  – Compare results with 9 main regions
  – Female non-manual wage
• Inside Wage
  – Average wage in hospital (but can just reflect grades)
  – Predicted wage based on NPRB regulation including
    regional allowances (Gosling-Van Reenen, 2006)
                                                         15
            Final Dataset
• 211 hospitals between 1996-2001
• 907 observations




                                    16
OUTLINE



1. Models: What is the effect of pay regulation?

2. Empirical models


3. Data


4. Results


5. Conclusions

                                                   17
                                      Table 2: Death Rates from AMI




Dependent variable          Ln(AMI Death Rate)          Ln(AMI Death Rate)   Ln(AMI Death Rate)
Estimation technique        OLS                         3 year annual Long   GMM-SYS
                                                        Differences
                            (1)                         (2)                  (3)

Ln (Area outside wage)       0.407***                     0.766**            0.460***
                             (0.124)                      (0.386)            (0.175)
Physicians share             -0.856***                    -0.654             -2.629**
                             (0.316)                      (0.616)            (1.258)
Qualified Nurses share       -0.480**                     -0.288             -1.416
                             (0.227)                      (0.467)            (0.959)
(omitted base is unqualified nurses/ health care assistants)

Hospital fixed effects      No                          No                   Yes
Casemix controls (14)       Yes                         Yes                  Yes
Year dummies (6)            Yes                         Yes                  Yes
Region dummies (10)         Yes                         No                   Yes
SC(1) p-value                                                                0.000
SC(2) p-value                                                                0.142
Hansen-Sargan p-value                                                        0.923
No of Hospitals             210                         133                  210
Observations                901                         345                  901              18
              Magnitudes (col 3)
• From 90th to 10th percentile of area outside wage
  difference is a fall of 33%. Associated with
   – a 14% fall in death rates (a quarter of the 62% 90-10 spread)
• Increase in physician share from 10th to 90th percentile
  is 7 percentage points. Associated with
   – 37% fall in AMI death rates (60% of 90-10 diff)
• Effect on AMI death rates of outside wage not dissimilar
  magnitude to drug based medical interventions (aspirin,
  beta blockers)
   – 10% increase in outside wages leads to 1 pp increase in AMI
     fatality
   – Heidenrich and McClellan (2001) increase use of aspirins by
     70% resulted in 3.3 p.p fall in AMI mortality

                                                                     19
                              Table 3: Productivity (FCEs per employee)




Dependent variable          Ln(Productivity)            Ln(Productivity)     Ln(Productivity)
Estimation technique        OLS                         3 year annual Long   GMM-SYS
                                                        Differences
                            (1)                         (2)                  (3)

Ln (Area outside pay)       -0.662***                    0.252               -0.551***
                            (0.145)                      (0.279)             (0.181)
Physicians share            3.837***                     0.248               3.909***
                            (0.360)                      (0.411)             (0.898)
Nurses share                0.386*                       0.006               1.736***
                            (0.201)                      (0.216)             (0.627)
(omitted base is unqualified nurses/health care assistants)
Hospital fixed effects      No                           No                  Yes
Casemix controls (39)       Yes                          Yes                 Yes
Year dummies (6)            Yes                          Yes                 Yes
Region dummies (10)         Yes                          No                  Yes
SC(1) p-value                                                                0.004
SC(2) p-value                                                                0.462
Hansen-Sargan p-value                                                        0.042
No of Hospitals             210                          133                 210
Observations                901                          345                 901                20
             Placebo tests
• Nursing homes
  – Provide medical care and other care services
    to elderly
  – Wages not regulated
  – 649 randomly selected homes: data for 1998
    and 1999
  – No evidence from OLS regression that
    outside pay associated with lower output
    (beds) per hour of staff time
                                               21
          Other placebo tests
• 42 service industries
• Dependent variable ln(revenues/worker)
• Only in 7/126 regression was outside
  wage neg. and significant
• Inside wage significant in almost all
• Suggests our finding of neg. effect of
  outside wages is a result of regulated pay
  maxima
                                               22
A possible mechanism: Agency nurses
• Higher outside wages associated with
  significantly greater use of agency staff
• Doubling of agency staff increases AMI death
  rates by 5%; no remaining effect of outside
  wages
• Agency nurses disproportionately in A and E
  wards
• Less effect on outside wages in productivity
  equation, but agency use still significant
• Use of agency staff related to MRSA rates (for
  2001-2002)

                                                   23
              Robustness checks
Upswings lead to poorer health in local labour market (e.g.
  Ruhm)
• Case-mix and local wages
   – AMI severity (HRG category) not related to outside wages
   – controls for HRG not significant for AMI deaths; total case-mix
     not significant for prody
• Are outside wages associated with higher community
  death rates?
   –   Our model implies weakly so
   –   Ruhm type argument – strong positive relationship
   –   We find weak n.s. positive relationship
   –   Also find no relationship between two key drivers of poor health-
       upswing relationship (pollution, smoking)

                                                                       24
              Robustness checks
Outside labor market affecting ambulance care
• More economic activity – slower road speeds (‘floor to
  door’)
   – Control for ambulance speeds
• Poorer quality of ambulance crew (door to needle time’)
   – Ambulance crew have no autonomy over which hospital to go to;
     administration of reperfusion (to stop clotting) by crews under
     0.6%.
Other tests
   – Financial pressure
   – Dynamics
   – Regional heterogeneity in impact outside wage



                                                                  25
                Conclusions
• Regulated pay costs lives (and productivity) in
  high outside wage areas
  – Higher death rates (and lower productivity) in areas
    where labour markets are tight
  – Some of this affect seems to operate through greater
    reliance on temporary agency staff
  – Not a feature of other UK service industries where
    (maximum) pay regulation does not operate
• Labour markets important for health on supply
  side of medical care as well as demand side
• Policy solution – allow wages to reflect local
  labour market conditions?
                                                       26
Back Up Slides




                 27
              Next Steps

• Other explanations – e.g. technology
  adoption (Acemoglu and Finkelstein,
  2006)?




                                         28
    Underlying structural model
• Hospitals choose mix of factors depending on
  environment and adjustment costs
• Factor with high adjustment costs changed more
  slowly
• Implies that lagged values predict future values
• Empirical identification requires that adjustment
  costs be sufficiently different across the factors
  to avoid weak instruments problems


                                                   29
                       System GMM
  Equation of interest

          yit  xit  ait ; ait  tt  i  uit
1) Difference equation eliminates firm fixed effects



Moment conditions allow use of suitably lagged levels of the variables as
instruments for the first differences (assuming levels error term serially
uncorrelated, see Arellano and Bond, 1991)

                         E[ xi ,t  s u it ]  0

       for s > 1 when uit ~ MA(0), and for s > 2 when uit ~ MA(1), etc.

        Test assumptions using autocorrelation test and Sargan

       Problem of weak instruments with persistence series…..
                                                                             30
                              System GMM
   2) Use lagged differences as instruments in the levels equation
   additional moment conditions (Arellano and Bover, 1998; Blundell and Bond, 2000):

                      E[xi ,t  s (i  uit )]  0

              for s = 1 when uit ~ MA(0), and for s = 2 when uit ~ MA(1)
Requires first moments of x to be time-invariant, conditional on common year dummies

Can test the validity of the additional moment conditions

We combine both sets of moments for difference and levels equations to
construct “System GMM” estimator

We assume all firm level variables are endogenous, while industry level variables are
exogenous in main specifications (relax in some specifications)



                                                                                        31
      Alternative to regulation
• Avoiding permanent pay increases
  (Houseman et al, 2003)
  – Pay more observable than in US
  – Differences in pay and quality across regions
    are persistent




                                                    32
         Big spread in productivity between hospitals (Fig 3)




Note: productivity measured by finished consultant episodes per worker 33
                                                 Sample characteristics

                                                          Mean        Standard deviation   Min      Max
AMI Variables
AMI death rate (55 plus)                                  21.14       4.483                7.454    36.941
Total AMI deaths (55 plus)                                79.99       33.83                13       294
Total AMI admissions (55 plus)                            385.02      160.84               151      1,348
Productivity and FCE (finished Consultant Episodes)
Productivity (total FCEs/ total clinical staffing)        31.17       7.57                 12.09    65.12
Total FCEs                                                58,664.58   24,515.83            13,490   138,984
Staffing Variables
Total clinical staffing (physicians + nurses + Allied     1675.79     692.25               398.61   4010.70
Health Professionals + Health Care Assistants)
Physicians share of staffing                              0.148       0.030                0.058    0.270
Qualified Nurses (plus qualified Allied Health            0.597       0.037                0.476    0.741
Professionals) share
Health Care Assistants share                              0.246       0.046                0.121    0.393
Hospital Expenditure Variables
Share of expenditure on agency staff as a proportion of   0.034       0.028                0.001    0.163
total expenditure (“Agency”)
Retained Surplus (£K) (745 obs)                           -206.1      1313.4               -11487   8505

                                                                                                             34
                                             Sample characteristics cont




Wages
Ln(Area outside wage)                                      9.60     0.140   9.27     9.99
Ln(nurse inside wage)                                      9.99     0.152   9.52     10.50
Ln(area inside wage)                                       10.09    0.110   9.53     10.45
Other variables
Directly Standardized Mortality rate in local area (per    723.43   77.13   518.73   944.21
100,000)
Teaching trust                                             0.111    0.341   0        1
Proportion of emergency admissions (to total admissions)   0.411    0.082   0.224    0.808
Proportion of transfer admissions (to total admissions)    0.160    0.066   0        0.448
Proportion of AMI admissions with HRG code E11             .162     0.075   0        0.667
HRG case mix index (892 obs)                               93.98    9.08    75.49    175.89
MRSA rate (216 obs)                                        0.169    0.088   0.02     0.55

                                                                                              35
          Large spread in death rates from AMI between hospitals




                       Worst 10%




                        Best 10%




• Improvements over time (cf. TECH Investigators)
• 1996: 10 percentage point (60%) difference between top and bottom (90th =27%,10th =17%)
                                                                                     36
            Simple model
• 2 areas: high outside wage “South” and
  low outside wage “North”
• Regulated wage the same in both areas
• Regulated wage lower than equilibrium
  wage




                                           37
           Wages

                                            Labour Supply,
                                            South
                                                     Labour Supply,
                                                     North
                   Labor Demand




Regulated Wage




                          NSOUTH   NNORTH           N, employment
                                                           38
           Wages

                                   Labour Supply,
                                   South

                   Labor Demand




Regulated Wage




                          NSOUTH            N, employment
                                                   39
           Wages

                                                Labour Supply,
                                                South

                   Labor Demand




Agency Wage



Regulated Wage




                              Agency staff



                          NPERMANENT   NTOTAL            N, employment
                                                                40
                                         Table 4: Controls for inside wages


Dependent     Ln(AMI      Ln(AMI          Ln(AMI      Ln(AMI      Ln(Producti Ln(Producti   Ln(Producti Ln(Producti
variable      Death Rate) Death Rate)     Death Rate) Death Rate) vity)       vity)         vity)       vity)
Estimation    OLS         Long            GMM-SYS GMM-SYS OLS                 Long          GMM-SYS GMM-SYS
technique                 Differences                                         Differences
                   (1)         (2)             (3)         (4)         (5)         (6)           (7)         (8)
Ln (Area      0.406***    0.765**         0.431**     0.431**     -0.659***   0.244         -0.547***   -0.548***
outside       (0.122)     (0.384)         (0.172)     (0.172)     (0.144)     (0.282)       (0.172)     (0.180)
pay)
Average       -0.286***      -0.126        -0.334**                 0.071     0.097         0.241**
inside wage (0.101)          (0.161)       (0.168)                  (0.115)   (0.128)       (0.125)
Predicted                                                 -0.371                                        0.264
ln(inside                                                 (0.716)                                       (0.342)
wage using
NPRB IV)
Physicians -0.498            -0.544        -1.787         -2.145*   3.750**   0.201         4.130***    3.979***
share         (0.342)        (0.641)       (1.236)        (1.286)   (0.390)   (0.394)       (0.930)     (0.904)
Nurses        -0.313         -0.253        -0.910         -1.002    0.347*    0.004         1.680***    1.734**
share         (0.224)        (0.471)       (0.822)        (0.856)   (0.207)   (0.212)       (0.607)     (0.628)
(omitted base is unqualified nurses/health care assistants)
SC(1) p-                                   0.000          0.000                             0.002       0.004
value
SC(2) p-                                   0.162          0.173                             0.436       0.485
value
Hansen- p-                                 0.795          0.716                             0.81        0.32
value
                                                                                                                41
                           Table 6: Placebo experiments: nursing homes


Dependent            Ln(revenues/hour) Ln(revenues/hour) Ln(revenues/hour) Ln(revenues/hour) Ln(output/hour)
variable
Estimation           OLS               OLS               OLS               OLS                OLS
technique
                     (1)               (2)               (3)               (4)                (5)

Ln (Area outside     -0.009            0.095             0.125             -0.084             -0.075
pay)                 (0.191)           (0.171)           (0.364)           (0.228)            (0.201)
Ln(Inside Pay)       0.166***          0.179***          0.166***          0.179***           0.049*
                     (0.031)           (0.030)           (0.037)           (0.044)            (0.028)
Ln (average hours)                     -0.466***
                                       (0.056)

Nursing Home         No                No                Yes               Yes                No
fixed effects?
Year dummies (1)     Yes               Yes               Yes               Yes                Yes
Region dummies       Yes               Yes               Yes               Yes                Yes
(10)

Number of            649               649               443               513                649
Nursing Homes
Observations         1,054             1,054             886               513                1,068

                                                                                                        42
A possible mechanism: Agency nurses




                                  43
               Figure 5: Agency Nurses, outside wages and AMI death rates



Dependent      Ln(Agen      Ln(AMI)    Ln(AMI)     Ln(AMI)        Ln          Ln          Ln
variable       cy)                                            (productivi (productivi (productivi
                                                                  ty)         ty)         ty)

               (1)        (2)         (3)         (4)         (5)         (6)         (7)
Ln (Area       2.851**                0.314*      0.175                   -0.805***   -0.729***
outside pay)    (1.138)               (0.170)     (0.202)                 (0.182)     (0.194)
Ln(Inside      0.077                  -0.494***   -0.477***               0.219       0.296**
Pay)           (1.045)                (0.153)     (0.161)                 (0.134)     (0.141)
Ln(Agency)                0.057**                 0.046*      -0.106***               -0.057***
                          (0.026)                 (0.024)     (0.027)                 (0.018)
No. of       176          176         176         176         176         176         176
hospitals
Observations 523          520         520         520         520         520         520




                                                                                            44
    All regressions include hosp fixed effects, region dummies, year effects.
                    Robustness checks: coefficient on outside wage
     Dependent variable                                Ln(AMI)    Ln(Productivity)   Obs.
                                                       (1)        (2)                (3)

1    Baseline                                          0.460**    -0.547***          901
                                                       (0.175)    (0.172)
2    Additional casemix controls                       0.427***   -0.556***          900 (for AMI)
                                                       (0.170)    (0.153)            892 (for prody)
3    Include hospital financial surplus                0.399**    -0.516***          745
                                                       (0.182)    (0.184)
4    Include lagged dependent variable: long-run [p-   0.508***   -0.572***          901
     value]                                            [0.008]    [0.020]
5    Drop Inner and Outer London                       0.304**    -0.383**           776
                                                       (0.156)    (0.173)
6    Drop big jumps in outside wage                    0.530**    -0.622***          885
                                                       (0.197)    (0.167)
7    Balanced Panel                                    0.600***   -0.612***          582
                                                       (0.207)    (0.163)
8    Regional outside wage                             0.609      -0.445             901
                                                       (1.022)    (0.587)
9    Regional outside wage (drop regional dummies)     0.520***   -0.493**           901
                                                       (0.172)    (0.169)
10   Include alternative total hospital employment     0.404**    -0.540**           901
     measure                                           (0.160)    (0.170)
11   Include higher order and cross product terms in   0.541***   -0.637***          901
     skill shares                                      (0.200)    (0.181)                              45
               Cost effectiveness
• Effect on AMI death rates of outside wage not dissimilar
  magnitude to drug based medical interventions (aspirin,
  beta blockers)
   – 10% increase in outside wages leads to 1 pp increase in AMI
     fatality; Heidenrich and McClellan (2001) increase use of
     aspirins by 70% resulted in 3.3 p.p fall in AMI mortality
• Cost of a life year saved by an 1% increase in (inside)
  nurse wages to all staff and an 1 p.p. increase in
  physician and nurses skill shares
   –   Increasing inside wages: $100,000
   –   physician share: $60,000
   –   nurse share: $36,000
   –   Value of QALY c $60,000
• Comparison with greater use of drug based medical
  technology, increasing wages for nurses and skill shares
  in hospitals expensive, but cheaper than the current cost
  of AMI treatment in the US (Skinner et al 2006)         46
               Higher nurse vacancy rates1 in stronger labor markets (fig 4)


                        Vacancy Rates for nurses                            predicted vacancy rate

           5


                                                                                                 Inner Lo


           4                                                     Outer Lo




                                                      South Ea

           3




           2
                                 West Mid
                                      East of
                               South We
                             Yorkshir
                          East MidNorth We
           1
                      North Ea


                9.4                             9.6                           9.8                           10
                                                      mean ln(outside wage)

1   Percentage of nurse posts that have been vacant for 3 months or more
                                                                       47
Higher use of agency nurses in stronger labor markets (Fig 6)

             Intensity of using agency nurse                     predicted Agency rate

 6




                                                                                         Inner Lo
 4                                                    Outer Lo




 2                                         South Ea
                           East of
                      West Mid

                    South We
                       North We
               East Mid
                  Yorkshir

           North Ea
 0
     9.4                             9.6                           9.8                              10
                                           mean ln(outside wage)

                                                                                                         48
Higher death rate from AMI admissions in stronger labor markets (fig 7)

                  AMI Rate                                           AMI = 1.96*W -0.10W2
                       Yorkshir
     23


                                                                                       Inner Lo
                                                          Outer Lo
                           North We
                                               South Ea
     22


                        South We



                               East of
     21
                North Ea Mid
                    East




     20
                         West Mid


          9.4                            9.6                           9.8                        10
                                               mean ln(outside wage)




                                                                                                       49
Changes in AMI death rates and changes in outside wages


                    AMI growth pa 1996-2001

    0

                                                                               West Mid
                                                                   East Mid
                                        Outer Lo                                 North Ea
                                                                                      South Ea


  -.02
                                                   Inner Lo

                                                                                           Yorkshir


         North We           South We

  -.04



                                       East of



  -.06
             .044              .046                  .048                .05                      .052
                                       av. outside wage gr 1996-2001


                                                                                                         50
               Magnitudes
• From 90th to 10th of area outside wage
  difference is a fall of 33%, associated with:
  – a 16% increase in productivity (a quarter of
    the 90-10 productivity difference)
• Increase in physician share from 90th to
  10th is 7 percentage points
  – 35% increase in productivity (58% of the 90-
    10 diff)

                                                   51

								
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