Test-Retest Reliability of the Shipley-Institute of Living Scale: Practice Effects or Random Variation

104 first-year female nursing students were group administered the Shipley-Institute of Living Scale. Retesting was conducted on subsamples at 2-wk., 1-mo., 2-mo., 3-mo., and 4-mo. intervals with subsample sizes of 17, 19, 19, 19, and 18, respectively. Although the actual differences were relatively small, consistent and significant increases were found for Abstract raw score, Conceptual Quotient and WAIS equivalent IQ. No significant differences were found for Vocabulary raw score. The results are discussed within the context of test-retest reliability, magnitude of the actual differences and the problem of practice effects.