An Investigation of the Type I Error and Power Properties of the Rank Transform Procedure in Factorial ANOVA

Abstract

This study examined the Type I error and power properties of the rank transform test when employed in the context of a balanced 2x2x2 fixed effects ANOVA. The results showed the rank transform procedure to be erratic with respect to both Type I error and power. Under some circumstances the test was both robust and powerful, whereas in other circumstances it was decidedly nonrobust and manifested power considerably below that of the usual ANOVA F test. It is recommended that researchers avoid this test except in those specific circumstances where its properties are well understood.