powerpoint lecture notes presentation chapter 4 research methods in the study of psychopathology...

PowerPoint Lecture Notes Presentation Chapter 4

Research Methods in the Study of Psychopathology

Abnormal Psychology, Eleventh Editionby

Ann M. Kring, Gerald C. Davison, John M. Neale, & Sheri L. Johnson

Copyright 2009 by John Wiley & Sons, NY 2

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.


Table 4.1 Research Methods in Psychopathology


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


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


Figure 4.2 Correlational vs. Experimental Studies


Table 4.2 Data for a Correlational Study with Diagnosis


Table 4.3 Data for Determining a Correlation


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 10Fig 4.2

Figure 4.3 Scatter Diagrams


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?


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


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


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).


Table 4.4 Lifetime Prevalence Rates of Selected

Disorders


Correlational Research: Behavioral Genetics

Index cases/Probands» Sample of individuals with

psychopathology Concordance

» Co-occurrence or similarity of diagnosis

Family studies» First degree relatives

(parents, children, siblings)– 50% shared genes

» Second degree relatives (aunts, uncles, grandparents)

– 25% shared genes

Twin studies» Monozygotic (MZ) twins

– 100% shared genes» Dizygotic (DZ) twins

– 50% shared genes» Equal environment assumption

Adoption studies» Study of adoptees who have

biological parents with psychopathology

Cross-fostering» Study of adoptees who have

adoptive parents with psychopathology

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



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


Table 4.5 Results of a Hypothetical Study Comparing CBT to

No Treatment for Depression

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



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


The Experiment

External validity» Extent to which results generalize beyond

the study– Would results apply to others besides the study

participants?


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


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)


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

Table 4.6 Meta-analysis: One-year prevalence rates for mental illness across

21 European studies



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.

powerpoint lecture notes presentation chapter 4 research methods in the study of psychopathology...

Documents

john wiley sons

var y var y

var ycopyright

var y negativehigher

variable y

correlational study

lower scores

directionpositivehigher