Table 2.

Predicting severity of cannabis dependence from frequency of use

		95% CI
	b	Lower	Upper	p
Step 1
Total R2 = 0.144, p < 0.001
Constant	1.046	0.636	1.473
Skunk	0.093	0.048	0.139	<0.001
Other grass	0.020	−0.029	0.070	0.436
Resin	0.025	−0.019	0.067	0.245
Step 2
ΔR2 = 0.003, p = 0.553
Total R2 = 0.147, p < 0.001
Constant	1.746	0.413	2.981
Skunk	0.096	0.051	0.143	<0.001
Other grass	0.018	−0.030	0.069	0.477
Resin	0.025	−0.018	0.067	0.245
Age	−0.003	−0.046	0.050	0.905
Gender	−0.380	−1.064	0.317	0.268
Step 3
ΔR2 = 0.023, p = 0.005
Total R2 = 0.170, p < 0.001
Constant	0.913	−0.874	2.537
Skunk	0.146	0.018	0.278	0.024
Other grass	0.014	−0.034	0.062	0.584
Resin	0.022	−0.021	0.064	0.298
Age	0.078	0.012	0.156	0.037
Gender	−1.030	−2.142	0.094	0.058
Age × skunk	−0.006	−0.010	−0.002	0.003
Gender × skunk	0.052	−0.019	0.121	0.160
Step 4
ΔR2 = −0.015, p = 0.138
Total R2 = 0.155, p < 0.001
Constant	−0.733	−2.865	0.922
Skunk	0.254	0.161	0.357	<0.001
Age	0.081	0.014	0.170	0.039
Age × skunk	−0.006	−0.010	−0.002	0.004

CI, Confidence interval.

Significant predictor variables are shown in bold.

Days of skunk use, but not other grass or resin, predicted higher Severity of Dependence Scale scores. The relationship between skunk use and severity of dependence became stronger as age decreased.