Chapter 5
Research Methods in the Study of
Abnormal Behaviour

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

Science and Scientific Methods
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Science: The pursuit of systematized knowledge through observation
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Latin scire – means “to know”
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Testability and Replicability
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A hypothesis must be amenable to systematic testing that could show it to be false
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What is observed must be replicable
• it must occur under prescribed circumstances not once, but repeatedly.

Science and Scientific Methods
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Theory:
• a set of propositions meant to explain a class of phenomena.
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The Role of Theory
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Primary goal of science is to advance theories to account for data, often by proposing cause –effect relationships
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Hypothesis
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Expectations about what should occur if a theory is true

How does theory get generated?
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Consider data that have been previously collected and then decide that a given way of thinking about the data is the most economical and useful.
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Sometimes creativity is employed (insight)

How do we judge a theory?
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What criteria are applied in judging the legitimacy of a theoretical concept?
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Operationism
• each concept take as its meaning a single observable and measurable operation.
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Each theoretical concept would be nothing more than one particular measurable event.
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However - if each theoretical concept is operationalized in only one way, its generality is lost.
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The need for multiple measures that tap into different facets of a concept

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

Theory-Building Case
Studies

The Rise Of Qualitative Research
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There has been a proliferation of qualitative research in psychology
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Qualitative research is similar to case study research in that the focus is on the unique and rich experiences of a small group of people who are studied in depth.
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Descriptive accounts with a subjective, idiographic emphasis are the focus rather than quantitative research

The Rise Of Qualitative Research
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However, well-done qualitative research can illuminate important phenomena that really seem to reflect issues and themes that matter to people and are central to understanding them.

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

Research Methods (cont.)
Correlational Method
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Is there a relationship between or among two or more variables?
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Measuring Correlation
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Correlation coefficient ( r )
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May take any value between +1.00 and -1.00
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Measures magnitude and direction of relationship
Statistical Significance
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Likelihood results of an investigation are due to chance
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Often set in psychology at p = .05

Statistical Significance

Applications of Correlation to
Psychopathology
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Whenever we compare people given one diagnosis with those given another or with people without a psychological diagnosis, the study is correlational.
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Often investigations in abnormal psychology are not recognized as correlational, perhaps because participants come to a laboratory for testing.
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Classificatory variables
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Variables that are already present and are simply measured by the researcher (i.e., disordered or not disordered, age, sex, social class, etc.).

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

Longitudinal modelling and group trajectories
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Developmental trajectories
• the levels of a particular behaviour over time
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Group-based trajectory
• is based on evidence that it is impossible to distinguish clear subgroups of participants in a sample and it is important to distinguish these groups both when considering the contribution of developmental factors and the best treatment options for these people (Nagin & Odgers, 2010).

Longitudinal modelling and group trajectories
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Multivariate statistical techniques are used to establish growth curves.
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Researchers using this approach can examine predictors of class membership as well as predictors of growth within a particular class.

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

Research Methods (cont.)
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Experimental Design cont.
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Internal validity
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Extent to which effect can be confidently attributed to manipulation of IV; Inclusion of at least one control group
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Confounders
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Internally invalid studies
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Placebo Effect
• an improvement in a physical or psychological condition that is attributable to a client ’s expectations of help rather than to any specific active ingredient in a treatment.
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Placebo control group; Double-blind procedures (when neither the researchers nor the clients are aware of who has been placed in the treatment and placebo control groups)
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External validity
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Can the results be generalized beyond immediate study?
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Analogue experiments
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The use of a related phenomenon (an analogue) in the lab
• behaviour is rendered temporarily abnormal through experimental manipulations.
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Randomized Controlled Trials (RTC)

Significance in Experiments
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Between-group variance
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The difference between groups
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The experimental effect
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Within-group variance
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The difference within the groups
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Statistical significance is tested by dividing the between group variance by a measure of the within-group variance.
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When the average difference between the two groups is large relative to the within- group variance, the result is more likely to be statistically significant.

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

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

Research Methods (cont.)
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Meta-Analysis
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The review of several studies in order to determine the effects of treatment, using a statistic called effect size
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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
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The combination of multiple meta-analyses is called meta-metaanalysis
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Despite difficulties and shortcomings, meta-analyses have been useful

Meta-analysis
other factors such as gender that may influence or qualify the results in some meaningful way

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