Some empirical results on the two-way analysis of variance by ranks
Hermanus Hofmeyr Lemmer · Communication in Statistics- Theory and Methods · 1980
Iman (1974) and Conover and Iman (1976) have shown by means of simulation studies that a rank transform, whereby the ordinary F-tests are applied to the ranks of the original observations in two-way experimental designs, presents a remarkably powerful method of analysis. In the present study it is shown that this rank transform is closely related to the procedure proposed by Lemmer and Stoker (1967) for the two-way analysis of variance. The main conclusions are that the Iman tests are generally slightly more powerful than those of Lemmer and Stoker, but that in the presence of interaction the latter tests for main effects are safer to use than the former because interaction tends to make the Iman tests for main effects significant even if no main effects exist.