abnormal PSYCHOLOGY Fourth Canadian Edition Chapter 5 Research Methods in the Study of Abnormal Behaviour Prepared by: Tracy Vaillancourt, Ph.D. Modified by: Réjeanne Dupuis, M.A.

Chapter Outline Science and Scientific Method Research Methods Testability and Replicability The Role of Theory Research Methods The Case Study Epidemiological Research The Correlational Method The Experiment Single-Subject Experimental Research Mixed Designs Meta-analysis

A. Science and Scientific Methods Science: The pursuit of systematized knowledge through observation Testability and Replicability A hypothesis must be amenable to systematic testing that could show it to be false Hypothesis: Expectations about what should occur if a theory is true The Role of Theory Primary goal of science is to advance theories Theory: A set of propositions meant to explain a class of phenomena

B. Research Methods Case Study The detailed study of one individual, based on a paradigm Providing detailed descriptions Collecting historical and biographical information Often includes details of therapy sessions Several case studies can be compared and analyzed for common elements through a specific method The case study as evidence Particularly useful to negate a universal theory or law Not useful to rule out alternative hypotheses Generating hypothesis Exposure to a large number of cases may allow the clinician to notice similarities of circumstances and outcomes

B. Research Methods II. Epidemiological Research Epidemiology: Study of frequency and distribution of a disorder in a population Data are gathered about the rates of a disorder and its possible correlates in a large sample or population Provides a general picture of a disorder Focuses on determining 3 features of a disorder: 1. Prevalence: Proportion of a population that has the disorder at a given point or period of time 2. Incidence: # of new cases of the disorder that occur in some period, usually a year 3. Risk factors: Conditions or variables that, if present, increases the likelihood of developing the disorder

B. Research Methods (cont.) III. Correlational Method Is there a relationship between or among 2 or more variables? Measuring Correlation Correlation coefficient (r) May take any value between +1.00 and -1.00 Measures magnitude and direction of relationship Statistical Significance Likelihood results of an investigation are due to chance Applications to Psychopathology

B. Research Methods (cont.) III. Correlational Method cont. Problems of Causality Critical drawback of correlational research Does not allow determination of cause-effect relationships Correlation between two variables tells us only that they are related or tend to co-vary with each Directionality problem How can we tell which is the cause and which is the effect? Correlation does not imply causation Prospective, longitudinal design helps resolve the directionality issue High-risk method: individuals with a predisposition are studied Third-variable problem

B. Research Methods (cont.) IV. Experimental Design Generally considered most powerful tool for determining causal relationships between events Involves (1) random assignment of participants to different conditions (2) manipulation of IV and measurement of DV Basic Features of Experimental Design 1. Researcher typically begins with an experimental hypothesis 2. Investigator chooses an independent variable (IV) that can be manipulated 3. Participants are assigned to the two conditions by random assignment 4. Researcher arranges for the measurement of a dependent variable (DV) 5. Produces an experimental effect

B. Research Methods (cont.) IV. Experimental Design cont. Internal validity Extent to which effect can be confidently attributed to manipulation of IV; Inclusion of at least one control group Confounders Placebo Effect Placebo control group; Double-blind procedures External validity Can the results be generalized beyond immediate study? Analogue experiments The use of a related phenomenon (an analogue) in the lab Randomized Controlled Trials (RTC)

B. Research Methods (cont.) V. Single-Subject Experimental Designs Participants are studied one at a time and experience a manipulated variable Reversal design or ABAB design Measurement of a specific behaviour at different times: (1) During an initial time period, the baseline (A) (2) During a period when treatment is introduced (B) (3) During a reinstatement of the condition that prevailed in the baseline period (A) (4) During the re-introduction of the experimental manipulation (B)

B. Research Methods (cont.) VI. Mixed Designs The combination of experimental and correlational designs Classificatory or correlational variables (e.g., having PTSD or not) are not manipulated nor created by the researcher Experiments demand the manipulation of a variable (e.g., 3 types of treatment for major depression)

B. Research Methods (cont.) VII. Meta-Analysis The review of several studies in order to determine the effects of treatment, using a statistic called effect size Meta-analysis can hardly provide definite answers b/c: 1. It is a complicated process that requires decisions at each of numerous phases or steps 2. Results of a meta-analysis are difficult to interpret Despite difficulties and shortcomings, meta-analyses have been useful

Summary

Copyright Copyright © 2011 John Wiley & Sons Canada, Ltd. All rights reserved. Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful. Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd. The purchaser may make back-up copies for his or her own use only and not for distribution or resale. The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.