Bayesian variable selection of linear mixed effect model under longitudinal data
Under the longitudinal data,the problem of how to use the Bayesian method to select the fixed effect and the random effect of the linear mixed effect model is discussed.For the selection of fixed effects,the likelihood function of the linear mixed model is first given,and then the Spike-and-Slab mixing prior is introduced for the fixed effects.For the covariance matrix in the random effects,the Inverse-Wishart distribution prior is given,and the active covariates in the fixed effects are marked by binary latent variables.The full conditional distribution and the corresponding Gibbs sampling algorithm are given.For the selection of random effects,Cholesky decomposition is used to reparameterize the covariance matrix in the linear mixed model,so that the function of the covariance parameters of the random effect distribution is used as the regression coefficient of the standard normal latent variable.By selecting the Spike-and-Slab mixing prior for the decomposed parameters in the random effect covariance matrix,the hierarchical Bayesian model is used to identify the random effects of zero variance,and the full conditional distribution and the corresponding Gibbs sampling algorithm are given.The simulation data is used to illustrate the effectiveness of the method.Finally,the model is applied to the actual data of 26 listed banks from February 2017 to February 2018 to verify the superiority of the method.