PowerPoint  Lecture Notes Presentation
Chapter 4
Research Methods in the Study of
Psychopathology
Abnormal Psychology, Eleventh Edition
by
Ann M. Kring, Gerald C. Davison, John M. Neale,
& Sheri L. Johnson
Science and Scientific Methods

Science
» The systematic pursuit of knowledge through
observation
» Scientists gather data to test theories

Theory
» Set of propositions developed to explain what is
observed
– A good theory is falsifiable


Allows for disconfirmation
Hypotheses
» Specific predictions about what will occur if a
theory is correct.
Copyright 2009 by John Wiley & Sons, NY
2
Table 4.1 Research Methods in
Psychopathology
Copyright 2009 by John Wiley & Sons, NY
3
Case Study

Detailed biographical
description of an
individual
»
»
»
»
Family history
Medical status
Educational background
Information about peer
and romantic
relationships
» Personality and
adjustment issues
» Current difficulties and
prior experiences in
therapy.

Usefulness
» Rich description,
especially helpful for rare
disorders
» Disprove hypothesis
» Generate hypotheses

Limitations
» Paradigm may influence
observations
» Cannot rule out
alternative explanations
Copyright 2009 by John Wiley & Sons, NY
4
Correlational Method

Do variable X and variable Y vary
together?
» Are they related in a systematic way?
– Do people who experience more stress have
more headaches?
Variables measured but not manipulated
 Cannot determine cause or effect

Copyright 2009 by John Wiley & Sons, NY
5
Figure 4.2 Correlational vs.
Experimental Studies
Copyright 2009 by John Wiley & Sons, NY
6

Table 4.2 Data for a
Correlational Study with
Diagnosis
Copyright 2009 by John Wiley & Sons, NY
7
Table 4.3 Data for Determining a
Correlation
Copyright 2009 by John Wiley & Sons, NY
8
Measuring Correlation

Correlation Coefficient
» Varies from -1.0 to +1.0
– e.g., +.9, -.65, +.32, -.70

Strength
» The higher the absolute value, the stronger the relationship
– (-.9 > +.6; +.9 > -.8)

Direction
» Positive
– Higher scores on Var X associated with higher scores on Var Y
» Negative
– Higher scores on Var X associated with lower scores on Var Y
Copyright 2009 by John Wiley & Sons, NY
9
Figure 4.3 Scatter Diagrams
Copyright 2009 by John Wiley & Sons, NY
Fig 4.2 10
Statistical and Clinical
Significance

Statistical significance
» Probability ≤ .05
» Can be influenced by number of participants
– Larger samples increase likelihood of significance

Clinical significance
» Is the association meaningful as well as statistically
significant?
Copyright 2009 by John Wiley & Sons, NY
11
Problems of Causality
Correlation does not imply causality
 Directionality problem

» Var X may cause Var Y
» Var Y may cause Var X

Third-variable problem
» Var Z causes both Var X and Var Y
Copyright 2009 by John Wiley & Sons, NY
12
Longitudinal vs Cross-sectional
designs

Longitudinal
» Studies participants over time
» Examines whether causes are present before
disorder develops
» High Risk Method
– Include only those who are at greatest likelihood of
developing a disorder
– Reduces the cost of longitudinal research

Cross-sectional
» Causes and effects measured at the same time
Copyright 2009 by John Wiley & Sons, NY
13
Epidemiological Research

Epidemiology
» Study of the distribution of disorders in a population and
possible correlates

Three features of a disorder
» Prevalence
» Incidence
» Risk Factors

The National Comorbidity Survey–Replication
» Large-scale national survey
» Used structured interviews to collect information on the
prevalence of several diagnoses (Kessler et al., 2005).
Copyright 2009 by John Wiley & Sons, NY
14
Table 4.4
Lifetime Prevalence Rates of Selected Disorders
Copyright 2009 by John Wiley & Sons, NY
15
Correlational Research:
Behavioral Genetics

Index cases/Probands

» Sample of individuals with
psychopathology

» Monozygotic (MZ) twins
– 100% shared genes
Concordance
» Dizygotic (DZ) twins
– 50% shared genes
» Equal environment assumption
» Co-occurrence or similarity
of diagnosis

Twin studies

Family studies
» Study of adoptees who have
biological parents with
psychopathology
» First degree relatives
(parents, children, siblings)
– 50% shared genes
» Second degree relatives
(aunts, uncles,
grandparents)
– 25% shared genes
Adoption studies

Cross-fostering
» Study of adoptees who have
adoptive parents with
psychopathology
Copyright 2009 by John Wiley & Sons, NY
16
Correlational Research:
Molecular Genetics

Linkage analysis method
» Study individual with disorder and family
members who also have the disorder
» Relies on the study of genetic markers.
– Genetic markers are diseases or characteristics with
a known chromosomal location of the genes
involved.

Association studies
» Examine the relationship between a specific
allele and a trait or behavior in the population
Copyright 2009 by John Wiley & Sons, NY
17
The Experiment


Provides information about
causal relationships
Involves:
» Independent variable
» Random assignment
» Dependent variable


Can evaluate treatment
effectiveness
Experimental Effect
» Differences between groups
Figure 4.3 Pennebaker et al., 1988
Copyright 2009 by John Wiley & Sons, NY
18
Table 4.5 Results of a Hypothetical Study
Comparing CBT to
No Treatment for Depression
Copyright 2009 by John Wiley & Sons, NY
19
Basic Features of
Experimental Design




The investigator manipulates an
independent variable
Participants are assigned to the conditions
by random assignment.
Researcher measures a dependent
variable that is expected to vary with
conditions of the independent variable.
Experimental effect
» Differences between conditions on the
dependent variable
Copyright 2009 by John Wiley & Sons, NY
20
The Experiment

Internal validity
» Extent to which experimental effect is due to
independent variable

Control Group
» Participants who do not receive treatment
» Standard against which treatment effectiveness is
judged.

Placebo
» Change or improvement due to participants’
expectations
Copyright 2009 by John Wiley & Sons, NY
21
The Experiment

External validity
» Extent to which results generalize beyond
the study
– Would results apply to others besides the study
participants?
Copyright 2009 by John Wiley & Sons, NY
22
Analogue Experiment

Experiments not always possible in
psychopathology
» Ethical or practical constraints

Examine related or similar behavior in
the lab
» Elicit stress or sadness
» College students who tend to be anxious
» Animal research
Copyright 2009 by John Wiley & Sons, NY
23
Single-Subject
Experimental Research


Examine how individual
participants respond to
changes in the
independent variable.
Reversal (ABAB)
Design
» The reversal
technique not always
possible
– Initial state may not
be recoverable.

Chorpita et al. (1977)
Copyright 2009 by John Wiley & Sons, NY
24
Integrating Findings
from Multiple Studies

Meta-analysis
» Identify relevant studies
» Compute effect size
– Transforms results to a
common scale

Smith et al. (1980)
» Meta-analyzed 475
outcome studies
» Results: Psychotherapy is
effective
Figure
4.5 Steps in Conducting a Meta-Analysis
Copyright 2009 by John Wiley & Sons, NY
25
Table 4.6 Meta-analysis: One-year prevalence
rates for mental illness across 21 European
studies
Copyright 2009 by John Wiley & Sons, NY
26
COPYRIGHT
Copyright 2009 by John Wiley & Sons, New
York, NY. All rights reserved. No part of the
material protected by this copyright may be
reproduced or utilized in any form or by any
means, electronic or mechanical, including
photocopying, recording or by any information
storage and retrieval system, without written
permission of the copyright owner.
Copyright 2009 by John Wiley & Sons, NY
27