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 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

Table 4.1 Research Methods in Psychopathology Copyright 2009 by John Wiley & Sons, NY

Copyright 2009 by John Wiley & Sons, NY 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

Copyright 2009 by John Wiley & Sons, NY 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

Figure 4.2 Correlational vs. Experimental Studies Copyright 2009 by John Wiley & Sons, NY

Copyright 2009 by John Wiley & Sons, NY Table 4.2 Data for a Correlational Study with Diagnosis Copyright 2009 by John Wiley & Sons, NY

Table 4.3 Data for Determining a Correlation Copyright 2009 by John Wiley & Sons, NY

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

Figure 4.3 Scatter Diagrams Copyright 2009 by John Wiley & Sons, NY Fig 4.2

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

Copyright 2009 by John Wiley & Sons, NY 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

Longitudinal vs Cross-sectional designs 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

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

Table 4.4 Lifetime Prevalence Rates of Selected Disorders Copyright 2009 by John Wiley & Sons, NY

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 Copyright 2009 by John Wiley & Sons, NY

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

Copyright 2009 by John Wiley & Sons, NY 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

Copyright 2009 by John Wiley & Sons, NY Table 4.5 Results of a Hypothetical Study Comparing CBT to No Treatment for Depression Copyright 2009 by John Wiley & Sons, NY

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

Copyright 2009 by John Wiley & Sons, NY 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

Copyright 2009 by John Wiley & Sons, NY 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

Copyright 2009 by John Wiley & Sons, NY 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

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

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

Copyright 2009 by John Wiley & Sons, NY Table 4.6 Meta-analysis: One-year prevalence rates for mental illness across 21 European studies Copyright 2009 by John Wiley & Sons, NY

Copyright 2009 by John Wiley & Sons, NY 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