highly significantp = 5.1 × 10 −8
Whilst both models indicated a highly significant relation between heritability and hierarchical level ( F -tests; linear: R 2 = 0.49, F 1,44 = 43, p = 5.1 × 10 −8 ; quadratic: R 2 = 0.67, F 2,43 = 44.1, p = 3.8 × 10 −11 ), the quadratic model fitted the data better than the linear model ( F -test, F 1,43 = 23.3, p = 1.8 × 10 −5 ) because heritability increased significantly from V1 to V3 ( t -test, t 8 = 2.38, p = 0.04).