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The Use of Extreme Groups to Test for the Presence of a Relationship

Published online by Cambridge University Press:  01 January 2025

Leonard S. Feldt
Leonard S. Feldt*
Affiliation:
State University of Iowa
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Abstract

Experimenters in psychology frequently investigate the relationship between two variables by selecting extreme groups on the first measure and comparing their mean scores on the second. This paper considers the efficacy of this procedure from the criterion of the power of the statistical tests. Optimal cutting points for the extreme groups are defined, and the power of the difference approach is compared to that of significance tests for the productmoment correlation coefficient.

Type
Original Paper
Information
Psychometrika , Volume 26 , Issue 3 , September 1961 , pp. 307 - 316
Copyright
Copyright © 1961 The Psychometric Society

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