Estimation in Covariance Components Models

Abstract

Estimation techniques for linear covariance components models are developed and illustrated with special emphasis on explaining computational processes. The estimation of fixed and random effects when the variances and covariances are known is presented in Bayesian terms, Point estimates of the unknown variances and covariances are computed using the EM algorithm for maximum likelihood estimation from incomplete data. The techniques are illustrated with data on law schools, field mice, and professional football teams.

Key Words:

• Covariance components
• Linear models
• Mixed models
• Random effects
• Maximum likelihood
• EM algorithm