Unreliability of difference scores: A paradox for measurement of change

Unreliability of difference scores: A paradox for measurement of change

Argues that the use of difference scores to measure change in experimental research has often been faulted on the grounds that errors of measurement are additive. It is suggested that in research concerned with differences between experimental treatment groups, the loss in reliability due to calcula...

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Bibliographic Details
Published in:Psychological bulletin Vol. 82; no. 1; pp. 85 - 86
Main Authors: Overall, John E, Woodward, J. Arthur
Format: Journal Article
Language:English
Published: Washington, etc American Psychological Association 01-01-1975
American Psychological Association, etc
Subjects:
Human
Statistical Correlation
Statistical Reliability
Online Access:Get full text
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Summary:Argues that the use of difference scores to measure change in experimental research has often been faulted on the grounds that errors of measurement are additive. It is suggested that in research concerned with differences between experimental treatment groups, the loss in reliability due to calculation of difference scores is not a valid concern because the power of tests of significance is maximum when the reliability of the difference scores is zero.
ISSN:0033-2909
1939-1455
DOI:10.1037/h0076158