Six modifications of the aligned rank transform test for interaction

Abstract

Testing for interactions in multivariate experiments is an important function. Studies indicate that much data from social studies research is not normally distributed, thus violating that assumption of the ANOVA procedure. The aligned rank transformation test (ART), aligning using the means of columns and rows, has been found, in limited situations, to be robust to Type I error rates and to have greater power than the ANOVA. This study explored a variety of alignments, including the median, Winsorized trimmed means (10%) and (20%), the Huber1.28 M-estimator, and the Harrell-Davis estimator of the median. Results are reported for Type I errors and power. Copyright © 2002 JMASM, Inc.