ROBUSTNESS OF STATISTICAL TESTS FOR MULTIPLICATIVE TERMS IN THE ADDITIVE MAIN EFFECTS AND MULTIPLICATIVE INTERACTION-MODEL FOR CULTIVAR TRIALS

The additive main effects multiplicative interaction model is frequent ly used in the analysis of multilocation trials. In the analysis of su ch data it is of interest to decide how many of the multiplicative int eraction terms are significant. Several tests for this task are availa ble, all of which assume that errors are normally distributed with a c ommon variance. This paper investigates the robustness of several test s (Gollob, F-GH1, F-GH2, F-R) to departures from these assumptions. It is concluded that, because of its better robustness, the F-R test is preferable. If the other tests are to be used, preliminary tests for t he validity of assumptions should be performed.