Reporting

By comparing with the earlier model without random effects for ram and ewe it can be seen that the standard errors for year and sex have changed little. These are fixed effects associated with the lowest layer in the fitted model.

With the reduction in residual variance one might have expected standard errors to be reduced too. This will often be so.

However, there is considerable imbalance in the way that ewes are distributed among genotype groups and years, as illustrated in Case Study 3, and this is probably reflected in the calculation of the standard errors.