The Use of Extreme Groups to Test for the Presence of a Relationship
Author:
- 1 September 1961
- journal article
- Published by Cambridge University Press (CUP) in Psychometrika
- Vol. 26 (3) , 307-316
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.Keywords
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