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Clinical Research by Zw48Ik7


									            Clinical Research
        Case Studies

Each has it’s place…but you should be aware of
the limitations of each approach.
Research Methods in Psychology
   By asking questions of a
    representative sample,
    researchers using the
    survey method can
    provide useful
    information about a much
    larger population.
   The wording of the
    questions can influence
    participants' responses.
Research Methods in Psychology

   A case study is an in-depth analysis of a
    single person or event.
   Although the findings of a case study may
    apply only to the person who was studied,
    they may provide direction for further
    study using other methods.
Research Methods in Psychology
   To study behavior in real-life settings,
    psychologists often use naturalistic
   This technique also may suggest research
    projects using more controlled
   In using naturalistic observation, the
    onlooker must be unobtrusive and avoid
    influencing the behavior being studied.
           Correlational Research
   The correlation technique
    indicates the degree of
    association between 2
   Correlations vary in direction:
       Positive association: increases in the
        value of variable 1 are associated with
        increases in the value of variable 2
       Negative association: increases in the
        value of variable 1 are associated with
        decreases in the value of variable 2
       No relation: values of variable 1 are
        not related to variable 2 values
   Correlations also vary in the strength of
    the association
       Zero correlation: no relationship between
        the 2 variables
       Strong correlation: knowing the value of one
        variable permits one to accurately estimate
        the value of the other variable
            Strong correlation can be positive or negative
   Correlations can be seen in scatter plots
                   A Zero Correlation
                                               •                •
                           •                        •


                   •                           •
                               •           •
                                                            •               •
                                   •                                •
             Low                           Independent variable                 High
A Moderate Positive Correlation
                                              • •
                                        • • •
                               •       • • •

                             • •
                         •              •
                   • •       •
               •         •
             Low              Independent variable   High
Correlation Difficulties
Research Methods in Psychology

   Because it can generate cause-and-effect
    statements, many psychologists believe
    that the experimental method is the most
    powerful research approach.
   By manipulating an independent variable
    (the cause), the researcher determines
    whether it influences the dependent
    variable (the effect).
         True Experimental Design
Select           Assign to          experimental      Compare
                  groups              stimulus       dependent
                                                   variable scores
                                                    on posttests

                             Pre                         Post
                             test                        test


                             Pre                         Post
                             test                        test
               Internal Validity

   Internal validity in experiments refers to:
   whether the independent variable actually
    does produce the effect it appears to have
    on the dependent variable.
   E.G. “Does the Rogerian therapy actually
    reduce anxiety symptoms in participants?”
       Does the class-room behavioral mgt program
        actually reduce problem behavior?
      Threats to Internal Validity
   Selection - the biases which may result in selection of
    comparison groups
   History - the specific events which occur between the
    first and second measurement
   Maturation - the processes within subjects which act as
    a function of the passage of time
   Instrumentation - the changes in the instrument,
    observers, or scorers which may produce changes in
   Statistical regression - the selection of subjects on
    the basis of extreme scores or characteristics
   Mortality: Experimental attrition -the loss of
Internal Validity
           Internal validity means
   that you have evidence that what you did
    in the study (i.e., the program) caused
    what you observed (i.e., the outcome) to
   The key issue is Causation
   True Experimental Design overcomes all of
    the internal validity threats
       Because subjects are randomized to
        treatment and control groups, there is no
        bias/favorites, both groups are equally likely
        to have same qualities
                External Validity

   The capacity to generalize findings to
    other groups of people and settings.
   Threats to external validity
       Selection Bias: Unrepresentative samples
       Reactive effects of experimental setting
       Multiple treatment interference
    Single Case Experimental
    Skinner – Experimental analysis of
    Much more rigorous than Case studies
    Establishing a baseline
    Two types of single case experimental
    1.   ABAB
    2.   Multiple-Baseline designs
   ABAB
       Baseline – Treatment – Baseline –
   Multiple-Baseline Design
       Home – School - Daycare
              Single-Case Design

                                        X       X
          X   X     X

Baseline, operant   Treatment,      Return to
rate                Reinforcement   Baseline, Extinction
      A                 B                   A
         Multiple Baseline Design

   Useful in testing for a treatment effect
    when you believe that the effect is
   Baseline data are collected on:
       2 or more behaviors for same individual
       Same behavior for 2 or more individuals
       Same behavior across 2 or more situations for
        the same individual.
        Multiple Baseline Design

             A   Baseline    Treatment
Behaviors,   B   Baseline    Baseline     Treatment
People, or   C   Baseline    Baseline     Baseline     Treatment
situations   D   Baseline    Baseline     Baseline     Baseline

             A   Baseline   CBT
Behaviors,   B   Baseline   Baseline     CBT
People, or   C   Baseline   Baseline     Baseline     CBT
situations   D   Baseline   Baseline     Baseline     Baseline

                  Dependent variable might be anxiety ratings
     Epidemiological Research
Definition: the study of the incidence, prevalence
  and distribution of illness/disease in a given

Incidence: the number of new cases of a disease
  during a given time interval, usually one year. It
  can be expressed as a proportion or as a rate.
Prevalence:the total number of cases of the
  disease in the population at a given time, or the
  total number of cases in the population, divided
  by the number of individuals in the population.

The Greek physician Hippocrates is usually
said to be the "father of epidemiology".
He is the first person known to have examined
the relationships between the occurrence of disease
and environmental influences. He coined the terms
 endemic (for diseases usually found in some places
 but not in others) and epidemic (for disease that are
 seen at some times but not others.

   Does not definitively establish causal
    relationships, but may still lead to
    preventative measures to stop the spread
    of disease
Dr. John Snow is famous for the suppression
of an 1854 outbreak of cholera in London's Soho
district. He identified the cause of the outbreak as
a public water pump on Broad Street and had the
handle removed, thus ending the outbreak. This has
been perceived as a major event in the history of
public health and can be regarded as the founding event
of the science of epidemiology.

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