Three univariate sex-limitation models were fit to the data for CD and for AAB, considered individually. The first model was the full sex-limitation model, which allows for both quantitative and qualitative sex differences as well as sex differences in phenotypic variances. In this model, seven parameters were estimated (Figure 1: am, cm, em, af, cf, and ef and either rA or rC). Because a model estimating both rA and rC simultaneously is not identified, these correlations were estimated separately in two different, non-nested models. The fits of these two non-nested models, that is, a model estimating rA versus a model estimating rC, were compared using the Akaike Information Criterion (AIC), and the model with the smaller AIC was selected as the best fitting model. The second model was the common effects model, which differs from the full sex-limitation model only in that parameters rA and rC were fixed to .50 and 1, respectively. Thus, the common effects model allows for quantitative sex differences as well as sex differences in phenotypic variances but not qualitative sex differences. The third model was
