Table 4.

Univariate MZ and DZ twin correlations and estimates of $a^2$, $c^2$, and $e^2$ for HV2, with nested AE model comparison.

Variable/statistic	TCICU	MLU	NDW	NTW	TNC
MZ
r	.74	.55	.52	.50	.50
95% CI	[.65, .82]	[.40, .68]	[.34, .67]	[.30, .65]	[.31, .38]
n pairs	107	102	75	75	75
DZ
r	.42	.37	.27	.32	.20
95% CI	[.28, .54]	[.22, .50]	[.09, .49]	[.13, .48]	[.00, .38]
n pairs	143	141	95	95	95
ACE model parameter estimates
$a^2$	.35	.50	.55	.59	.53
95% CI	[.07, .66]	[.14, .71]	[.09, .67]	[.14, .71]	[.22, .66]
$c^2$	.33	.11	.00	.00	.00
95% CI	[.03, .56]	[.00, .39]	[.00, .35]	[.00, .34]	[.00, .20]
$e^2$	.32	.39	.45	.40	.47
95% CI	[.25, .42]	[.28, .53]	[.33, .63]	[.29, .59]	[.34, .66]
AE model vs. ACE model
Fit statistics
AIC (ACE)	328.582	368.39	319.38	268.87	326.51
BIC (ACE)	−784.54	−697.08	−542.60	−385.97	−539.03
AIC (AE)	331.21	366.95	317.38	267.66	324.51
BIC (AE)	−785.02	−699.58	−545.32	−388.21	−541.76
AE model parameter estimates
$a^2$	.69	.63	.55	.56	.53
95% CI	[.60, .75]	[.50, .72]	[.39, .67]	[.44, .71]	[.34, .66]
$a^2$	.31	.37	.45	.40	.47
95% CI	[.25, .40]	[.28, .50]	[.33, .61]	[.29, .56]	[.34, .66]

Note. Boldface type indicates lower Akaike information criterion (AIC) and Bayesian information criterion (BIC) values (indicating a better fitting model) for each model-fitting comparison. AIC (ACE/AE): AIC for the ACE/AE model. BIC (ACE/AE): BIC for the ACE/AE model.