Table 2.

Comparison of the (i) full Cholesky decomposition, (ii) uni-directional Peer Group Deviance causes Cannabis Use (PGD→CU), (iii) uni-directional Cannabis Use causes Peer Group Deviance (CU→PD), and (iv) reciprocal causation (PGD↔CU) models at 15 to 17 years, 18 to 21 years and 22 to 25 years.

15–17 years	−2LL	df	Δ−2LL	Δdf	p	BIC
Cholesky	6921.31	3546				−3214.81
PGD→CU	6935.70	3548	14.39	2	<0.001	−3211.38
CU→PGD	6923.23	3548	1.92	2	0.38	−3217.62
PGD↔CU	6921.34	3547	0.03	1	0.86	−3216.68

18–21 years	LL	df	Δ2LL	Δdf	p	BIC
Cholesky	7722.99	3541				−2804.56
PGD→CU	7752.65	3543	29.66	2	<0.001	−2793.50
CU→PGD	7726.97	3543	3.98	2	0.14	−2806.33
PGD↔CU	7723.28	3542	0.29	1	0.59	−2806.30

22–25 years	−2LL	df	Δ2LL	Δdf	p	BIC
Cholesky	7725.38	3542				−2805.25
PGD→CU	7744.32	3544	18.94	2.00	<0.001	−2799.54
CU→PGD	7729.08	3544	3.70	2.00	0.16	−2807.16
PGD↔CU	7728.00	3543	2.62	1.00	0.11	−2805.82

−2LL = log-likelihood

Δ−2LL=change in log-likelihood which is asymptotically distributed as a chi-square

BIC = sample size adjusted Bayesian Information Criterion

All PGD and CU thresholds are adjusted for the linear effects of age at interview