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Testing Whether Independent Treatment Groups have Equal Medians

Published online by Cambridge University Press:  01 January 2025

Rand R. Wilcox
Rand R. Wilcox*
Affiliation:
University of Southern California
*
Requests for reprints should be sent to Rand Wilcox, Department of Psychology, University of Southern California, Los Angeles, CA 90089-1061.
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Abstract

The paper suggests new methods for comparing the medians corresponding to independent treatment groups. The procedures are based on the Harrell-Davis estimator in conjunction with a slight modification and extension of the bootstrap calibration technique suggested by Loh. Alternatives to the Harrell-Davis estimator are briefly discussed. For the special case of two treatment groups, the proposed procedure always had more power than the Fligner-Rust solution, as well as the procedure examined by Wilcox and Charlin. Included is an illustration, using real data, that comparing medians, rather than means, can yield a substantially different conclusion as to whether two distributions differ in terms of some measure of central location.

Keywords

L-statisticsHarrell-Davis estimatorbootstrapkernel density estimatessmoothing
Type
Original Paper
Information
Psychometrika , Volume 56 , Issue 3 , September 1991 , pp. 381 - 395
Copyright
Copyright © 1991 The Psychometric Society

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