. Author manuscript; available in PMC: 2018 Jun 1.

Published in final edited form as: Psychol Addict Behav. 2017 Apr 17;31(4):385–392. doi: 10.1037/adb0000279

Table 3.

Zero-inflated Poisson models of percent days used alcohol and cannabis across the 36-week follow-up period.

Substance Use Outcomes	Alcohol Use		Cannabis Use
	EXP	CONTROL	EXP	CONTROL
N	28	30	21	22
	N/(%) or M (SD)	N/(%) or M (SD)	N/(%) or M (SD)	N/(%) or M (SD)
N/% with >1% days use	19 (67.9%)	19 (63.3%)	15 (71.0%)	11 (50.0%)
Mean (SD) % Days use if days ≥1%	8.3% (9.6%)	12.0% (11.2%)	26.6% (29.9%)	36.5% (37.6%)
Days Used Odds Ratio for ≥ 1% vs. 0% ZIP model test	Odds Ratio (95% CI)=1.21 (.38,3.85) X²(2)=.11, p=.74		Odds Ratio (95% CI)=2.67 (0.69,10.36) X²(2)=2.02, p=.15
% Days Used Ratio of Means ZIP model test	Ratio of Means (95% CI)=.74 (.59,.92) X²(2)=7.41, p=.007		Ratio of Means (95% CI)=.63 (.53,.41) X²(2)=30.24, p=<.0001

Note: EXP=Experimental Condition; CONTROL=Control Condition; CI= Confidence Interval; ZIP=Zero Inflated Poisson. Analyses included SES and Cannabis Dependence as covariates.