BMC Med Res Methodol 2015 Apr 22;15:37. Epub 2015 Apr 22.
Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, 211166, , Jiangsu, People's Republic of China.
Background: In many medical studies the likelihood ratio test (LRT) has been widely applied to examine whether the random effects variance component is zero within the mixed effects models framework; whereas little work about likelihood-ratio based variance component test has been done in the generalized linear mixed models (GLMM), where the response is discrete and the log-likelihood cannot be computed exactly. Before applying the LRT for variance component in GLMM, several difficulties need to be overcome, including the computation of the log-likelihood, the parameter estimation and the derivation of the null distribution for the LRT statistic.
Methods: To overcome these problems, in this paper we make use of the penalized quasi-likelihood algorithm and calculate the LRT statistic based on the resulting working response and the quasi-likelihood. Read More