Fitting the full model to the dichotomized trait values of test scores yields the correct conclusion for data simulated under the additive genetic model (Table 5), showing little support for any but homozygous main effects of the two candidate loci. However, significance levels are much reduced under the full model, reflecting substantial loss of information when the continuous variables are dichotomized. Fitting a model that ignores all possible non-additive effects yield highly significant estimates of the additive main effects of both loci but the gain in significance presumes prior knowledge of the genetic architecture that might not be justified in practice (compare results for other simulated genetic models).
