Contradictions Can Never a Paradox Resolve

作者：John E. Overall · 发表于：Applied Psychological Measurement · 年份：1989 · DOI：10.1177/014662168901300408 · 被引用次数：23 · 研究领域：Psychometric Methodologies and Testing、Behavioral and Psychological Studies、Cognitive Abilities and Testing

The fact that difference scores tend to be less reli able than the original measurements from which they are calculated should not be a matter of concern in testing the significance of treatment-induced change. The reliabilities of the original measurements are im portant because unreliability attenuates correlation, and substantial correlation between prescores and post- scores is required for difference scores to be of value in controlling for individual differences. Reliability notwithstanding, difference scores provide superior control over true baseline differences in quasi-experi mental research, whereas the analysis of covariance (ANCOVA) is generally preferable for baseline control in randomized experimental designs. Index terms: analysis of covariance, baseline correction, difference scores, measurement of change, reliability.