Table 4.

Model parameters for mid-term drinking outcomes (6-month follow-up)

Predictors	Coeff. IRR or Ba	SE	[95% CI]	z	p
Drinking frequency
Baseline drinking frequency	1.07	0.005	[1.06, 1.08]	15.57	<.001
PNF	0.93	0.06	[0.83, 1.05]	-1.16	.25
DBF	0.97	0.06	[0.86, 1.10]	-0.44	.66
Total alcohol quantity
Negative binomial process
Baseline alcohol quantity	1.02	0.001	[1.01, 1.02]	16.64	<.001
PNF	0.89	0.06	[0.77, 1.02]	-1.65	.10
DBF	0.82	0.06	[0.71, 0.94]	-2.81	.01
Zero-inflated process
Baseline alcohol quantity	-0.02	0.01	[-0.04, -0.005]	-2.53	.01
Alcohol problems
Negative binomial process
Baseline alcohol problems	1.08	0.01	[1.06, 1.09]	10.73	<.001
PNF	0.93	0.10	[0.75, 1.14]	-0.70	.48
DBF	0.75	0.08	[0.61, 0.93]	-2.59	.01
Zero-inflated process
Baseline alcohol problems	-0.71	0.19	[-1.09,-0.33]	-3.66	<.001

Notes: Coeff. = coefficients; IRR = incident rate ratio; CI = 95% confidence interval; PNF = personalized normative feedback; DBF = decisional balance feedback.

^aFor the negative binomial process, coefficients are represented as IRRs. For the zero-inflated process, raw coefficients (B) are presented.