Table 4.

Statistics of the fitted models

Model number	Model	Estimated parameters	− 2 LL	df	AIC	Compared to model	Δ − 2 LL	Δ df	p
Saturated model
0	Saturated model with thresholds equal for MZ and DZ twins, correlations equal for boys and girls	36	61,852.35	30,693	466.35
1	Thresholds equal across SES	20	62,132.26	30,709	714.26	0	279.91	16	3.63e−50
2	Correlations equal across SES	28	61,915.42	30,701	513.42	0	63.07	8	1.16e−10
3	Thresholds equal across countries	24	62,155.55	30,705	745.55	0	303.19	12	1.00e−57
4	Correlations equal across countries	30	61,865.90	30699	467.90	0	13.54	6	0.04
ACE model
5	ACE model based on the results of the final saturated model	33	62,175.85	30,696	783.85
6	A, C, and E equal across low, medium, and high SES	27	62,234.37	30,702	830.37	5	58.52	6	9.01e−11
6.1	A, C, and E equal across low and medium SES	30	62,179.76	30,699	781.76	5	3.91	3	0.27
6.2	A, C, and E equal across low and high SES	30	62,218.81	30,699	820.81	5	42.96	3	2.51e−09
6.3	A, C, and E equal across medium and high SES	30	62,215.38	30,699	817.38	5	39.53	3	1.34e−08

Model number corresponds to the description in “Results”. − 2 LL refers to the minus 2 log likelihood. df represents the number of degrees of freedom of the model. Δ − 2 LL refers to the difference in minus 2 log likelihood of the compared models. Δ df refers to the difference in number of degrees of freedom of the compared models. p corresponds to the p value of the difference in model fit between the compared models