The purpose of this study was to explicate two issues concerning the standard and rank based test of homogeneity of slopes. Two alternative ranking methods intended to address nonnormality and additive treatment effect patterns were developed and compared in terms of their ability to control Type I error. The results replicated previous findings of inflated Type I error rates with leptokurtic curves and with rank based tests with some patterns of additive treatment effects. The new nonparametric procedures generally control Type I error although they were slightly inflated with skewed distributions.
Klockars, Alan J. and Moses, Tim P.
"Type I Error Rates For Rank-Based Tests Of Homogeneity Of Slopes,"
Journal of Modern Applied Statistical Methods: Vol. 1
, Article 54.
Available at: http://digitalcommons.wayne.edu/jmasm/vol1/iss2/54