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1VA Long Beach Healthcare Systems Medical Center, CA, USA. charter.richard_a@long-beach.va.gov
Journal of Clinical and Experimental Neuropsychology
|January 10, 2002
Summary
This study addresses the minimum subject number for reliability and validity testing. It challenges the proposed 400-subject minimum, offering a nuanced perspective on sample size adequacy in research.
Area of Science:
- Psychometrics
- Research Methodology
Background:
- Dr. Cicchetti challenged the minimum subject requirement for psychometric validation.
- Charter (1999) suggested a minimum of 400 subjects for various reliability and validity coefficients.
Discussion:
- This report critically evaluates the 400-subject minimum proposed by Charter.
- It examines the implications of sample size on split-half, coefficient alpha, retest, alternate-forms, validity, and inter-rater reliability.
Key Insights:
- The adequacy of sample size is context-dependent and not a universal number.
- Statistical power and effect size should guide sample size determination over arbitrary thresholds.
Outlook:
- Further research should focus on developing evidence-based guidelines for sample size in psychometric studies.
- Promoting flexible, context-specific approaches to sample size justification is crucial.
