In this paper, we develop a simple diagnostic test for the random-effects distribution in mixed models. The test is based on the gradient function, a graphical tool proposed by Verbeke and Molenberghs to check the impact of assumptions about the random-effects distribution in mixed models on inferences. Inference is conducted through the bootstrap. The proposed test is easy to implement and applicable in a general class of mixed models. The operating characteristics of the test are evaluated in a simulation study, and the method is further illustrated using two real data analyses.
All Keywords
【저자키워드】 bootstrap, mixed models, goodness-of-fit, Random effects, gradient function,
【저자키워드】 bootstrap, mixed models, goodness-of-fit, Random effects, gradient function,