SOME TESTS FOR VARIANCE-COMPONENTS USING GENERALIZED P-VALUES

The concept of a generalized p value, introduced by Tsui and Weerahand i, is applied for testing hypotheses in two situations, testing the si gnificance of a variance component in a general balanced mixed model w hen an exact F test does not exist and comparing random-effects varian ce components in two independent balanced mixed models. Extensions to the unbalanced cases are also indicated. The proposed test is compared with the test based on the Satterthwaite approximation through their simulated Type I error probabilities. The simulations indicate that th e test based on the generalized p value has Type I error probabilities less than the chosen significance level most of the time, whereas the Type I error probabilities of the Satterthwaite approximate test can be much larger than the significance level. The results are illustrate d using two examples.