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ERIC Number: ED205536
Record Type: RIE
Publication Date: 1981-Apr
Reference Count: 0
The Unreliability of Difference Scores for the Measurement of Change: A Paradox?
Lam, Tony C. M.
The objective of this paper is to examine the relationship between the unreliability of difference scores and the power of tests of significance in an attempt to determine the validity of the paradox for the measurement of change presented by Overall and Woodward: that the power of tests of significance is maximum when the reliability of the difference scores is zero. It is concluded that this paradox is more superficial than real. A negative covariation between power and reliability of difference may occur if subject-by-time interaction variance is significantly greater than measurement error variance, and a positive relationship if the opposite is true. (Author/BW)
Publication Type: Speeches/Meeting Papers; Reports - Research
Education Level: N/A
Authoring Institution: N/A
Identifiers: Difference Scores; Interaction (Statistical)
Note: Paper presented at the Annual Meeting of the American Educational Research Association (65th, Los Angeles, CA, April 13-17, 1981).