Institute of Electronic Technology, the PLA Information Engineering University School of Statistics, Renmin University of China

Varying-coefficients mixed model (VCMM) is
proposed for longitudinal data and the other correlated data. This
model allows flexible functional dependence of the response variable
on the covariates by using varying-coefficients linear part to
present the covariates effects, while accounting the within-subject
correlation by using random effect. In this article, the coefficient
functions are estimated by using smoothing spline and restricted
maximum likelihood is used to estimate the smoothing parameters and
the variance components simultaneously. The performance of the
proposed method is evaluated though some simulation studies, which
show that both the coefficient functions and variance components
could be estimated well for the VCMMs with all kinds of covariance
structures.