Table 2.

Hierarchical linear modeling of alcohol consumption per interactive voice response (IVR) call day

Predictors	Estimate	SE	t	df	probust	Event rate ratio	[95% CI]
Model 1
Intercept	-2.793	0.337	-8.30	69	.001
IVR day number (t)	0.003	0.001	2.46	5483	.014	1.003	[1.001, 1.006]
Module retrieval (t – 1)	-0.161	0.098	-1.64	5483	.050a	0.852	[0.725, 1.000]a
Urge to drink	1.178	0.133	8.83	69	.001	3.248	[2.490, 4.237]
Weekend opportunity	0.138	0.047	2.91	5483	.004	1.148	[1.046, 1.260]
Drug use other than alcohol	0.539	0.133	4.06	5483	.001	1.714	[1.321, 2.223]
Model 2
Intercept	-2.790	0.336	-8.31	69	.001
IVR day number (t)	0.003	0.001	2.42	5482	.016	1.003	[1.001, 1.006]
Module retrieval (t – 1)	-0.491	0.268	-1.83	5482	.034a	0.612	[0.393, 0.951]a
Urge to drink	1.278	0.145	8.80	69	.001	3.591	[2.689, 4.795]
Weekend opportunity	0.142	0.046	3.07	5482	.003	1.153	[1.053, 1.262]
Drug use other than alcohol	0.512	0.146	3.50	5482	.001	1.669	[1.253, 2.224]
Module Retrieval × Urge	0.249	0.142	1.75	5482	.n.s.
Model 3
Intercept	-4.253	0.544	-7.82	68	.001
Initial resolution status	1.100	0.247	4.45	68	.001	3.003	[1.835, 4.914]
IVR day number (t)	0.003	0.001	2.34	5480	.019	1.003	[1.001, 1.006]
Module retrieval (t – 1)	-0.493	0.267	-1.85	5480	.032a	0.611	[0.394, 0.948]a
Urge to drink	1.284	0.149	8.64	69	.001	3.611	[2.686, 4.854]
Weekend opportunity	0.137	0.046	2.97	5480	.003	1.147	[1.048, 1.256]
Drug use other than alcohol	-0.246	0.392	-0.63	5480	.n.s.
Module Retrieval × Urge	0.254	0.141	1.80	5480	.n.s.
Resolution Status × Drug Use	0.301	0.129	2.33	5480	.020	1.352	[1.049, 1.742]

Notes: IVR day number (1–168) = time effect; p_robust = significance based on robust standard errors (SE; see text); CI = confidence interval based on analyses with robust SEs; n.s. = not significant.

^aEffects for module retrieval were tested one tailed at p ≤ .05.