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Self selection and sample selection in a treatment study of social phobia
H R Juster1, R G Heimberg, B Engelberg
1Department of Psychology, University at Albany, State University of New York 12205, USA.
Behaviour Research and Therapy
|March 1, 1995
Summary
Patient self-selection and study criteria can affect treatment outcome research. This study found that despite some demographic differences, patients who refused or were excluded from a social phobia study responded similarly to treatment as those who accepted.
Area of Science:
- Psychiatry
- Clinical Psychology
- Research Methodology
Background:
- External validity of treatment studies can be compromised by patient self-selection and sample selection criteria.
- The impact of these selection biases on generalizability of findings is not well understood.
- Previous research has rarely investigated these effects in treatment outcome studies.
Purpose of the Study:
- To compare subjects who accepted random assignment with those who refused (self-selected) and were excluded (sample-selected) in a social phobia treatment study.
- To assess the impact of self-selection and sample selection on the generalizability of treatment outcome findings.
- To determine if different selection groups respond differently to cognitive-behavioral treatment for social phobia.
Main Methods:
- Compared "acceptors" (randomly assigned) with "refusers" (self-selected) and "excluded" (sample-selected) subjects in a social phobia pharmacologic and cognitive-behavioral treatment study.
- Analyzed demographic and pretreatment clinical measures across the three groups.
- Compared posttreatment outcomes for refusers and excluded subjects (treated with cognitive-behavioral treatment) against acceptors assigned to the same treatment.
Main Results:
- "Acceptors" differed from "refusers" in annual income and social support, suggesting potential resource availability influences.
- Despite demographic differences, acceptors and refusers showed minimal differences in pretreatment clinical functioning.
- Excluded subjects did not differ demographically or clinically from acceptors or refusers.
- All three groups exhibited similar responses to cognitive-behavioral treatment for social phobia, with few significant posttreatment differences.
Conclusions:
- Self-selection and sample selection may influence some sample characteristics but do not appear to significantly alter clinical similarity or treatment response.
- The findings suggest that cognitive-behavioral treatment for social phobia is effective across different patient selection groups.
- The study supports the generalizability of findings from this comparative outcome study despite potential selection biases.