VCE-5, a package for the estimation of dispersion parameters.

OBJECTIVES VCE-5 is a program package to estimate dispersion parameters under a general linear model. It covers all options of previous versions of VCE (Groeneveld and García-Cortés, 1998). Additionally, statistical models cover variety of possibilities like heterogeneous covariance components for residual as well as other random effects, models with longitudinal data, random regression, multi-environment analyses, crossbreeding designs, etc. Additive and dominance relationship are implemented for direct, maternal and paternal components. The same trait may have different models as in case of the first litter in gilts and the subsequent litter in sows. Most of the models can be solved by any of the three methods available. Dispersion parameters are obtained by restricted maximum likelihood (REML) using analytical gradients, a MonteCarlo EM as well as Gibbs sampling. VCE-5 is written in Fortran 90. The algorithms are the same as in previous versions, insuring that dispersion parameters are always within parameter space (Groeneveld, 1994; Neumaier and Groeneveld, 1998).