Questions to be addressed

The questions to be addressed herein are:

• Are there differences in weaning weight among the four genotypes?
• Are there other factors or covariates that can be included in the analysis to improve the precision with which weaning weight comparisons can be made among genotypes?
• One such covariate might be age of dam (ewe). How best can the association between age of dam and weaning weight be parameterised? Another possible covariate is age at weaning? How can this also be best incorporated in the model?


• In answering these questions we shall first produce some summary statistics and graphs to understand how the data are distributed in relation to the different covariates.
• Having decided how best to define our statistical model we shall, using weaning weight as the response variable, fit a least squares analysis of variance incorporating the various factors and covariates to reflect the patterns we have observed.