False positive rates (type 1 error rates) for testing interaction in common disease with main effect at one locus (Schema 2).

a<p>logistic regression model with 1 df test for the correct genetic model.</p>b<p>logistic regression model with 4 df test by coding genotypes as factors.</p><p>The disease prevalence is assumed 0.02. The significance level is set as 0.01.