We examined patterns of correlations across the psychiatric factors and 49 biobehavioral traits28, 101 metrics of brain morphology29, and circadian activity across 24 hours30. Results for brain morphology are presented in Supplementary Figures 3 and 4 and Supplementary Table 4, as none of these associations were significant at a Bonferroni-corrected threshold for 174 tests (P < 2.87 × 10−4). To evaluate the extent to which external traits operated through a given factor, we calculated χ2difference tests comparing a model in which the trait predicted the factor only to one in which it predicted the individual disorders of a given factor (or the first-order factors in the case of analyses using the p-factor model; Supplementary Fig. 5). We term the χ2difference across these two models the Qtrait heterogeneity index (Fig. 2). A significant Qtrait index indicates that the pattern of associations between the individual disorders and the external trait is not well accounted for by the factor.
