... Statistical Inference. Springer-Verlag, New York, USAthennnd matrices, then tr(AB) > 0 (Graybill, 1969).Hence,Original articleHeterogeneous variances in Gaussian linear mixed ... 1994)Summary - This paper reviews some problems encountered in estimating heterogeneous variances in Gaussian linear mixed models. The one-way and multiple classificationcases ... for sire and residual variances to assess sources of heterogeneity in within-herd variances of milk and fat records in Holstein. Herd size and within-herd meanswere associated...