Estimation of genetic covariance from joint offspring-parent and sib-sib statistics.

Formulae for calculating the variances and covariances of estimates of genetic variance or covariance from offspring-parent and sib covariance data are presented. The model consists of a one-way classification of families with unequal numbers of offspring, where normally distributed traits x (a parental measure), y and z (offspring measures) are recorded. Procedures for pooling offspring-parent and sib covariance estimators are discussed. An application of the results to estimating genetic variance is presented, and the offspring-parent and sib covariance estimators and a pooled statistic are compared in terms of exact and asymptotic formulae. Implications for experimental design and allocation of experimental resources are also reported.