0

tandfonline.com – The Wilcoxon–Mann–Whitney Procedure Fails as a Test of Medians

tandfonline.com har udgivet en rapport under søgningen “Teacher Education Mathematics”:

ABSTRACT

To illustrate and document the tenuous connection between the Wilcoxon–Mann–Whitney (WMW) procedure and medians, its relationship to mean ranks is first contrasted with the relationship of a t-test to means. The quantity actually tested:

Pr ^(X1<X2)+ Pr ^(X1=X2)/2

is then described and recommended as the basis for an alternative summary statistic that can be employed instead of medians. In order to graphically represent an estimate of the quantity: Pr(X1 < X2) + Pr(X1 = X2)/2, use of a bubble plot, an ROC curve and a dominance diagram are illustrated. Several counter-examples (real and constructed) are presented, all demonstrating that the WMW procedure fails to be a test of medians. The discussion also addresses another, less common and perhaps less clear cut, but potentially even more important misconception: that the WMW procedure requires continuous data in order to be valid. Discussion of other issues surrounding the question of the WMW procedure and medians is presented, along with the authors’ teaching experience with the topic. SAS code used for the examples is included as supplementary material.

Link til kilde

Troels Gannerup Christensen

Jeg er ansat som adjunkt hos Læreruddannelsen i Jelling, hvor jeg underviser i matematik, specialiseringsmodulet teknologiforståelse, praktik m.m. Jeg har tidligere været ansat som pædagogisk konsulent i matematik og tysk hos UCL ved Center for Undervisningsmidler (CFU) i Vejle og lærer i udskolingen (7.-9. klasse) på Lyshøjskolen i Kolding. Jeg er ejer af og driver bl.a. hjemmesiderne www.lærklokken.dk og www.iundervisning.dk, ggbkursus.dk og er tidligere fagredaktør på matematik på emu.dk. Jeg går ind for, at læring skal være let tilgængelig og i størst mulig omfang gratis at benytte.

Leave a Reply

0 Kommentarer
Inline Feedbacks
View all comments