Table 3.

Model Fit Comparisons for the Twin Moderation Models.

Model	−2lnL (df)	χ2Δ (df)	p	AIC	BIC	Adj. BIC	DIC
Full Sample (N = 964 Twins)
Full Model	2227.64 (780)	–	–	667.64	−1226.73	10.78	−509.96
Nested Submodels:
Constrain A, C, E quad mods	2232.75 (783)	5.11 (3)	.16	666.75	−1233.18	9.09	−513.65
Constrain linear and quad A mods	2255.69 (782)	28.05 (2)	<.001	691.69	−1218.71	21.98	−500.10
Constrain linear and quad C mods	2228.25 (782)	0.61 (2)	.74	664.25	−1232.43	8.26	−513.82
Constrain all C mods and A quad only	2229.97 (783)	2.33 (3)	.51	663.97	−1234.57	7.71	−515.04
Constrain all C mods and E quad only	2232.68 (783)	5.04 (3)	.17	666.68	−1233.21	9.06	−513.68
Constrain all C mods, A, E quad	2232.82 (784)	5.18 (4)	.27	664.82	−1236.14	7.72	−515.70
Constrain linear and quad E mods	2241.62 (782)	13.98 (2)	<.001	677.62	−1225.74	14.95	−507.13
Constrain all linear and quad moderators for A, C, and E	2242.05 (786)	14.41 (6)	.03	670.05	−1237.53	9.50	−515.25
Pre-Menarcheal Twins Only (N = 530 Twins)
Full Model	1420.77 (510)	–	–	400.77	−713.50	95.09	−244.75
Nested Submodels:
Constrain A, C, E quad mods	1421.80 (513)	1.03 (3)	.79	395.80	−721.27	91.98	−249.85
Constrain linear and quad A mods	1423.33 (512)	2.56 (2)	.28	399.33	−717.71	93.95	−247.22
Constrain linear and quad C mods	1420.97 (515)	0.20 (2)	.90	396.97	−718.89	92.77	−248.40
Constrain all C mods, A quad only	1421.62 (513)	0.85 (3)	.84	395.62	−721.36	91.89	−249.94
Constrain all C mods, E quad only	1421.63 (513)	0.96 (3)	.81	395.73	−721.30	91.95	−249.89
Constrain all C mods, A, E quad	1422.05 (514)	1.28 (4)	.86	394.05	−723.93	90.90	−251.69
Constrain linear and quad E mods	1431.66 (512)	10.89 (2)	.004	407.66	−713.55	98.12	−243.05
Constrain A, C, Moderators	1433.49 (516)	12.72 (6)	.047	401.49	−723.80	94.21	−249.63

Note. −2lnL = minus twice the log-likelihood; χ²_Δ = chi-square change; AIC = Akaike information criterion; BIC = Bayesian information criterion; Adj. BIC = sample-size adjusted BIC; DIC = deviance information criterion; Full Model = model with paths and all moderators; mods = moderators; quad = quadratic or non-linear moderators; A = additive genetic effects; C = shared environmental effects; E = nonshared environmental effects. Each nested model is compared to the full model when calculating the χ²_Δ and degrees of freedom. The best-fitting models are noted by bolded text and borders. Unstandardized estimates (with 95% confidence intervals in parentheses) from the best-fitting models were as follows: Full Sample: a = −0.81 (−1.04, −0.49), c = 0.36 (−0.59, .59), e = −0.42 (−0.64, −0.26), β_XM = 0.21 (.02, 0.43), β_YM = 0, β_ZM = −0.36 (−0.58, −0.11), β_X2M² = 0; β_Y2M² = 0; β_Z2M² = 0.05 (−0.01, .12); Premenarcheal Twins Only: a = 0.78 (0.34, 1.06), c = −0.41 (−0.62, 0.62), e = −0.48 (−0.66, −0.33), β_XM = −0.26 (−0.48, −0.04), β_YM = 0, β_ZM = −0.20 (−0.31, −0.09), β_X2M² = 0; β_Y2M² = 0; β_Z2M² = 0.