title: A goodness-of-fit test for the random-effects distribution in mixed models.
abstract: 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.
authors.affiliation: 1 Interuniversity Institute for Biostatistics and statistical Bioinformatics, KU Leuven, Leuven, Belgium.
authors.forename: Achmad
authors.initials: A
authors.lastname: Efendi
authors.affiliation: 1 Interuniversity Institute for Biostatistics and statistical Bioinformatics, KU Leuven, Leuven, Belgium.
authors.forename: Reza
authors.initials: R
authors.lastname: Drikvandi
authors.affiliation: 1 Interuniversity Institute for Biostatistics and statistical Bioinformatics, KU Leuven, Leuven, Belgium.|2 Interuniversity Institute for Biostatistics and statistical Bioinformatics, Universiteit Hasselt, Hasselt, Belgium.
authors.forename: Geert
authors.initials: G
authors.lastname: Verbeke
authors.affiliation: 1 Interuniversity Institute for Biostatistics and statistical Bioinformatics, KU Leuven, Leuven, Belgium.|2 Interuniversity Institute for Biostatistics and statistical Bioinformatics, Universiteit Hasselt, Hasselt, Belgium.
authors.forename: Geert
authors.initials: G
authors.lastname: Molenberghs
mesh_terms: D056808:Biostatistics / Q000379:methods; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D016208:Databases, Factual / Q000706:statistics & numerical data; D004827:Epilepsy / Q000188:drug therapy; D005533:Foot Dermatoses / Q000188:drug therapy; D006801:Humans; D015233:Models, Statistical; D014009:Onychomycosis / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data
keywords: Bootstrap; goodness-of-fit; gradient function; mixed models; random effects