clinical psychology

1. THE ROLE OF RESEARCHTHE ROLE OF RESEARCH
IN CLINICAL PSYCHOLOGYIN CLINICAL PSYCHOLOGY
Lecture 10Lecture 10

2.  Research lays a foundation of knowledge forResearch lays a foundation of knowledge for
understandingunderstanding
 Also provides a body of evidence to guideAlso provides a body of evidence to guide
clinical practiceclinical practice
 Provides a basis for reliability & validity ofProvides a basis for reliability & validity of
psychological tests & assessment methodspsychological tests & assessment methods
 Helps in identifying effective interventionsHelps in identifying effective interventions

3.  Also provides ideas for new directions andAlso provides ideas for new directions and
applicationsapplications
 A variety of methods are usedA variety of methods are used
 Clinical psychology research: conducted inClinical psychology research: conducted in
many different settingsmany different settings

4. RESEARCH DESIGNSRESEARCH DESIGNS
There are four basic types of researchThere are four basic types of research
designs from which to choose:designs from which to choose:
descriptive designs,descriptive designs,
correlational designs,correlational designs,
experimental designs,experimental designs,
and single-case designs.and single-case designs.

5. DESCRIPTIVE RESEARCH DESIGNSDESCRIPTIVE RESEARCH DESIGNS
 Used to report on the prevalence or incidence of aUsed to report on the prevalence or incidence of a
human problem in the populationhuman problem in the population
 Often an important first step in research on a particularOften an important first step in research on a particular
problem or disorderproblem or disorder
 Primarily concerned with accurate measurement of thePrimarily concerned with accurate measurement of the
problem & sample’s representativenessproblem & sample’s representativeness
 Do not attempt to predict or understand the causes ofDo not attempt to predict or understand the causes of
a problema problem
 Used most frequently in epidemiological studiesUsed most frequently in epidemiological studies

6. CORRELATIONAL RESEARCHCORRELATIONAL RESEARCH
DESIGNSDESIGNS
 Used to determine the degree of associationUsed to determine the degree of association
between two (or more) variablesbetween two (or more) variables

7. The degree of relationshipThe degree of relationship
 (How closely variables are related)(How closely variables are related)
 Expressed as a number between -1 and +1Expressed as a number between -1 and +1
 So-called correlation coefficientSo-called correlation coefficient
The direction of the relationshipThe direction of the relationship
 indicated by the "indicated by the "--" and "" and "++" signs" signs
 A student's grade and the amount of studying done:A student's grade and the amount of studying done:
Positive correlationPositive correlation
 Stress and health: Negative correlationStress and health: Negative correlation
 LIMITATION: No Cause & Effect relationshipLIMITATION: No Cause & Effect relationship

8. EXPERIMENTAL RESEARCHEXPERIMENTAL RESEARCH
DESIGNSDESIGNS
 Involve the control or manipulation of theInvolve the control or manipulation of the
independent variable (s) to determine their effect onindependent variable (s) to determine their effect on
the dependent variable (s)the dependent variable (s)
 Independent variable is under the control of theIndependent variable is under the control of the
researcherresearcher
 Experimental designs are used in two primaryExperimental designs are used in two primary
ways:ways:
1.1. to study the possible causal relationshipto study the possible causal relationship
2.2. to evaluate the effectiveness of an interventionto evaluate the effectiveness of an intervention

9. ESSENTIAL CHARACTERISTICS OF ANESSENTIAL CHARACTERISTICS OF AN
EXPERIMENT:EXPERIMENT:
 To be "experimental", a study must meetTo be "experimental", a study must meet
two conditions:two conditions:
1. (a)1. (a) EXPERIMENTAL INDEPENDENT VARIABLEEXPERIMENTAL INDEPENDENT VARIABLE
1. (b) EXPERIMENTAL CONTROL1. (b) EXPERIMENTAL CONTROL
2. RANDOM ASSIGNMENT2. RANDOM ASSIGNMENT
(all subjects have an equal chance of being(all subjects have an equal chance of being
exposed to each condition)exposed to each condition)

10.  The GOALThe GOAL of experimental researchof experimental research
methods: to establish cause-and-effectmethods: to establish cause-and-effect
relationships between variablesrelationships between variables
 The PURPOSE:The PURPOSE: to eliminate alternativeto eliminate alternative
hypotheseshypotheses
 EXAMPLE: if a new form of psychotherapy isEXAMPLE: if a new form of psychotherapy is
more effectivemore effective

11. TYPES OF VARIABLESTYPES OF VARIABLES
 1. INDEPENDENT VARIABLE (IV):1. INDEPENDENT VARIABLE (IV):
 2. DEPENDENT VARIABLE (DV):2. DEPENDENT VARIABLE (DV):
 3. CONTROL VARIABLES:3. CONTROL VARIABLES:
 4. RANDOM VARIABLES:4. RANDOM VARIABLES:
 5. CONFOUNDING VARIABLES:5. CONFOUNDING VARIABLES:

12. CONCEPTS INCONCEPTS IN
EXPERIMENTAL RESEARCHEXPERIMENTAL RESEARCH
1.1. RELIABILITYRELIABILITY
2. INTERNAL VALIDITY2. INTERNAL VALIDITY
3. EXTERNAL VALIDITY3. EXTERNAL VALIDITY

13. HYPOTHESESHYPOTHESES
 Experimental research methods revolve aroundExperimental research methods revolve around
hypotheseshypotheses

14. TYPES OF HYPOTHESESTYPES OF HYPOTHESES

15. 1. Research hypothesis1. Research hypothesis
 results are due to the Independent Variableresults are due to the Independent Variable
2. Null hypothesis2. Null hypothesis
 differences are due to chancedifferences are due to chance
3. Alternative hypotheses3. Alternative hypotheses
 results are due to factors other than IVresults are due to factors other than IV

16. ALTERNATIVE HYPOTHESESALTERNATIVE HYPOTHESES
1. Subject effect or selection effect:1. Subject effect or selection effect:
(results are due to systematic differences in research(results are due to systematic differences in research
participants)participants)
Common solution:Common solution: Matching or random assignmentMatching or random assignment
to groupsto groups
2. History effect:2. History effect: (results are due to events outside the(results are due to events outside the
experiment)experiment)
Common solution:Common solution: A control group which will beA control group which will be
exposed to the same history but not the new form ofexposed to the same history but not the new form of
psychotherapypsychotherapy

17. 3. Maturation effect:3. Maturation effect: (results are due to changes(results are due to changes
within subjects over time)within subjects over time)
Common solution:Common solution: A control group which is measuredA control group which is measured
over the same period of time but does not receive theover the same period of time but does not receive the
new psychotherapynew psychotherapy
4. Experimenter expectancy effect or Experimenter4. Experimenter expectancy effect or Experimenter
bias:bias: (results are due to the experimenter's actions or(results are due to the experimenter's actions or
expectations)expectations)
Common solution:Common solution: Use independent judges or moreUse independent judges or more
objective measurements of the dependent variableobjective measurements of the dependent variable

18. 5. Demand characteristics or Hawthorne5. Demand characteristics or Hawthorne
effect:effect: (results are due to subjects'(results are due to subjects'
expectations of desired behavior)expectations of desired behavior)
Common solution:Common solution: Blind and double-blindBlind and double-blind
designs help avoid these problemsdesigns help avoid these problems
6. Testing effect or reactivity:6. Testing effect or reactivity: (results are due(results are due
to the data gathering procedures)to the data gathering procedures)
Common solution:Common solution: Use a control group which isUse a control group which is
also measured, but without the therapyalso measured, but without the therapy

19. 7. Regression artifact: (7. Regression artifact: (results are due to extremeresults are due to extreme
scores moving toward the mean over time)scores moving toward the mean over time)
Common solution:Common solution: Use a control group which hasUse a control group which has
similar characteristics (mental health scores) butsimilar characteristics (mental health scores) but
which does not receive the new therapy.which does not receive the new therapy.
8. Instrumentation:8. Instrumentation: (results are due to an irregularity(results are due to an irregularity
in measuring tools)in measuring tools)
Common solution:Common solution: Select or develop a better measureSelect or develop a better measure

20. 9. Halo effect:9. Halo effect: (the researcher's expectations about(the researcher's expectations about
certain subjects based on some subjectcertain subjects based on some subject
characteristics)characteristics)
Common solutions:Common solutions: Random assignment, blind judges,Random assignment, blind judges,
more objective measuresmore objective measures
10. Attrition or mortality effect:10. Attrition or mortality effect: When subjects dropWhen subjects drop
out of an experimentout of an experiment
Common solution:Common solution: Find out why participants droppedFind out why participants dropped
outout
11. Other non-specific factors11. Other non-specific factors and alternativeand alternative
hypotheses that may arise in a particular experimenthypotheses that may arise in a particular experiment

21. A COMMENT:A COMMENT:
With so many ways to go wrong, it may seem from thisWith so many ways to go wrong, it may seem from this
list that all research is hopelessly flawed. In a sense,list that all research is hopelessly flawed. In a sense,
this is accurate. There is no such thing as perfectionthis is accurate. There is no such thing as perfection
in an experimental design. However, perfection is notin an experimental design. However, perfection is not
the best standard to use.the best standard to use.
It is suggested that we look for studies that are goodIt is suggested that we look for studies that are good
enough. Even though there are always ways to refineenough. Even though there are always ways to refine
and extend any study, there are many experimentsand extend any study, there are many experiments
that are good enough to base strong conclusions on.that are good enough to base strong conclusions on.

22. TYPES OF EXPERIMENTALTYPES OF EXPERIMENTAL
DESIGNSDESIGNS

23. A: TRUE EXPERIMENTAL DESIGNSA: TRUE EXPERIMENTAL DESIGNS
 Attempt to eliminate most alternativeAttempt to eliminate most alternative
hypotheses (e.g., history, maturation, andhypotheses (e.g., history, maturation, and
regression)regression)
 May make the situation too artificial.May make the situation too artificial.
Types:Types:
A. RANDOMIZED GROUPS DESIGN or BETWEEN-GROUPSA. RANDOMIZED GROUPS DESIGN or BETWEEN-GROUPS
DESIGNDESIGN
B. REPEATED MEASURE DESIGN or WITHIN-SUBJECTB. REPEATED MEASURE DESIGN or WITHIN-SUBJECT
DESIGNDESIGN
C. MIXED MODEL DESIGNS OR COMPLEX DESIGNSC. MIXED MODEL DESIGNS OR COMPLEX DESIGNS

24. B: SINGLE-SUBJECT DESIGNSB: SINGLE-SUBJECT DESIGNS
 So-called "N=1" designsSo-called "N=1" designs
 Used most often in clinical psychology situations withUsed most often in clinical psychology situations with
behavior modificationbehavior modification
 Note: this is experimental research; not Case studyNote: this is experimental research; not Case study
research.research.
 Can provide strong internal validity, but typicallyCan provide strong internal validity, but typically
suffers from low external validity.suffers from low external validity.
 A series of regular and planned observations is takenA series of regular and planned observations is taken
over a period of time; and divided into sessions ofover a period of time; and divided into sessions of
baseline and treatment conditions.baseline and treatment conditions.

25. I. ABA OR REVERSAL DESIGNI. ABA OR REVERSAL DESIGN
 A = Baseline observation, B = Treatment, A = 2A = Baseline observation, B = Treatment, A = 2ndnd
observation (ABA)observation (ABA)
II. ABAB DESIGNII. ABAB DESIGN
 Provides a replication of the AB comparisonProvides a replication of the AB comparison
A = Baseline observation, B = Treatment, A = 2A = Baseline observation, B = Treatment, A = 2ndnd
observation, B = Treatment again (ABAB)observation, B = Treatment again (ABAB)

26. CONCLUSION TOCONCLUSION TO
EXPERIMENTAL DESIGNSEXPERIMENTAL DESIGNS
 Which design is best?Which design is best?
 Each type of research design is useful forEach type of research design is useful for
addressing some questions and hypothesesaddressing some questions and hypotheses
and not others.and not others.
 Ethical constraints can also limit the types ofEthical constraints can also limit the types of
research designsresearch designs