Table 2.

Sequential logit model giving the estimated effects of marijuana, alcohol, and selected covariates on the odds of sex-risk decisions

Predictor	Wald χ2 (df = 4)a	Equation
		Sexually activeb Yes/no	Partner typec Casual/main	Unprt. sex w maind Unprt./Prt.	Unprt. sex w casuale Unprt./Prt.
Years age	12.20*	1.04 (0.97, 1.12)	0.92 (0.75, 1.13)	1.29** (1.12, 1.51)	1.13 (0.87, 1.47)
Race (white)	8.44	1.50 (1.12, 2.01)**	0.59 (0.27, 1.28)	1.01 (0.51, 1.97)	1.19 (0.33, 4.29)
College (yes)	19.55**	0.57 (0.42, 0.75)**	0.93 (0.45, 1.92)	0.71 (0.40, 1.28)	2.48 (0.60, 4.16)
Employed (yes)	2.57	0.96 (0.75, 1.23)	0.73 (0.38, 1.42)	1.31 (0.74, 2.31)	0.62 (0.20, 1.87)
Impulsivity	5.13	1.03 (1.00, 1.07)	0.99 (0.92, 1.07)	0.99 (0.92, 1.07)	1.04 (0.94, 1.16)
Any recent cocaine (yes)	2.73	0.82 (0.61, 1.12)	1.23 (0.61, 2.51)	1.44 (0.65, 3.18)	0.92 (0.32, 2.62)
Used alcohol (yes)	43.15**	1.46 (1.24, 1.73)**	1.61 (1.08, 2.38)*	1.15 (0.84, 1.60)	0.79 (0.46, 1.37)
Used marijuana (yes)	32.49**	1.60 (1.33, 1.93)**	1.18 (0.69, 2.00)	0.88 (0.59, 1.31)	2.58 (1.10, 6.09)*

Significance tests and 95% confidence interval estimates are based on robust variance estimators adjusted for within subject clustering (n = 308 participants observed for 28,198 person days)

^*P < 0.05,

^**P < 0.01

^aTest of the null hypothesis that the four coefficients giving the estimated effect of the predictor on the four decisions are jointly 0

^bEstimated effect on the odds (95% CI) of being sexually active

^cEstimated effect on the odds (95% CI) of a casual partner on days when sexually active

^dEstimated effect on the odds (95% CI) of having unprotected sex on days when sexually active with a main partner

^eEstimated effect on the odds (95% CI) of having unprotected sex on days when sexually active with a casual partner