Solution: Female Laysan Finch Weight in Relation to Beak Size Summary Weight increases significantly with increased beak size, even after accounting for the correlated variation in overall size (as measured by the two skeletal variables). The beak

Weight increases significantly with increased beak size, even after accounting for the correlated variation in overall size (as measured by the two skeletal variables). The beak measurements are very highly correlated with each other, so (1) it is impossible to disentangle their relationships with weight, and (2) they are redundant so that if one is in the model neither of the others explains much additional variation. For these data these conclusions could be reached either by dividing weight by one or both skeletal variables and regressing the resulting ratio on the beak measurements, or by including the skeletal variables as additional explanatory variables in a multiple regression analysis.