Comparing the Reliability of Difference Scores and Residuals in Analysis of Covariance
- 1 December 1991
- journal article
- Published by SAGE Publications in Educational and Psychological Measurement
- Vol. 51 (4) , 803-807
- https://doi.org/10.1177/001316449105100401
Abstract
In pretest-posttest designs, residual scores created in the analysis of covariance commonly are preferred to difference scores because the latter suffer from reliability problems. This paper develops the reliability of residuals adjusted for a single covariate for comparison to the reliability of difference scores. Comparisons reveal that little is gained by analysis of covariance, which also suffers from reliability problems as the pretest and posttest reliabilities decrease and as their intercorrelation increases.Keywords
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