logistic models, which aims to assess the additional effect that the cross-product contributes. The bound has been shown to be tight, and most nonsignificant interactions can be pruned. In all three models, age, sex and the first PCA dimension calculated from the AIMs were included as covariates. Permutation tests were performed to identify empirical thresholds to correct the P-value for multiple tests of main effects. Parallelized permutation tests were developed and conducted using a high performance computing facility with 120 processors to identify empirical thresholds and avoid inflating the P-value for epistatic effects.
