Table 4.

Test Statistics for Cholesky Decomposition Model for Deviant Peers with Constraints across Age

Model	−2lnL	df	Δ−2lnL (df)	p value	AIC
1. Fully age unconstrained (baseline)	133.06	66
2. Fully age constrained	164.68	75	31.61 (9)	.0002	14.68
3. Constrain A at all ages	141.23	69	8.17 (3)	.04	3.23
4. Constrain A at ages 15 and 18 years	137.28	67	4.22 (1)	.04	3.28
5. Constrain A at ages 18 and 21 years	134.15	67	1.09 (1)	.30	0.15
6. Constrain C at all ages	146.71	69	13.65 (3)	.003	8.71
7. Constrain C at ages 15 and 18	135.46	67	2.40 (1)	.12	1.46
8. Constrain C at ages 18 and 21	138.68	67	5.62 (1)	.02	4.68
9. Constrain E at all ages	143.84	69	10.78 (3)	.01	5.84
10. Constrain E at ages 15 and 21	138.55	67	5.49 (1)	.02	4.55
11. Constrain E at ages 18 and 21	143.12	67	10.06 (1)	.002	9.12

Notes.

Abbreviations: A=additive genetic effects. C=shared environmental effects. E=nonshared environmental effects. −2lnL= −2 times the log likelihood. AIC=Akaike Information Criteria.

Δ−2lnL=differences in 2lnL values between the sex-constrained but age unconstrained model (model 1). All χ² tests compare models to model 1 (fully age unconstrained model). All models constrain parameters across sexes.