Abstract
The relationship between variables in applied and experimental research is often investigated by the use of extreme (i.e., upper and lower) groups. Recent analytical work has provided an extreme groups procedure that is more powerful than the standard correlational approach for all values of the correlation and extreme group size. The present article provides procedures to optimize power by determining the relative number of subjects to use in each of two stages of data collection given a fixed testing budget.
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The opinions or assertions contained herein are those of the writers and are not to be construed as official or reflecting the views of the Navy Department.
Edward F. Alf, Jr. is also affiliated with the Department of Psychology, San Diego State University.
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Abrahams, N.M., Alf, E.F. Relative costs and statistical power in the extreme groups approach. Psychometrika 43, 11–17 (1978). https://doi.org/10.1007/BF02294085
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DOI: https://doi.org/10.1007/BF02294085