Table 2.

Retention and Marijuana Use Outcomes by Treatment Condition

	Treatment								Contrast
	MET/CBT + CM		DC + CM		MET/CBT		DC				Interaction (t)
Variable	M	SE	M	SE	M	SE	M	SE	MET/CBT vs. DC (t)	CM/vs. no CM (t)		dfs	n
Total no. of sessions	6.0	0.44	5.4	0.4	4.9	0.41	4.2	0.43	1.47	2.72*	2.19*	1, 131	136
Days of marijuana use (%)	0.64	0.06	0.75	0.1	0.73	0.05	0.71	0.06	1.03	0.6	0.63	1, 126	131a
Longest duration of continuous abstinence, days	27.3	3.6	26.4	3.6	21.5	3.58	17.3	4.83	1.21	2.06*	1.17	1, 124	129b
No. of marijuana-negative urine specimens submitted	2.3	0.38	2.0	0.4	1.3	0.37	0.9	0.37	0.87	2.79*	1.82	1, 127	132c
No. of consecutive marijuana-negative urine specimens	2.2	0.36	1.8	0.4	1.3	0.35	0.8	0.35	1.21	2.73*	1.99*	1, 127	132c
Marijuana-positive urine specimens (%)	0.5	0.07	0.7	0.1	0.7	0.07	0.7	0.07	1.27	1.39	2.24*	1, 127	132c

Note. Motivational enhancement therapy/cognitive–behavioral therapy (MET/CBT) = motivational enhancement plus skills therapy; DC = individual drug counseling; CM = contingency management. Interaction = contrast of MET/CBT + CM > DC/CM = MET/CBT without CM > DC/CM.

^aN = 131, ns = 33, 32, 34, and 32 for the MET/CBT + CM, DC + CM, MET/CBT without CM, and DC without CM groups, respectively.

^bN = 129, ns = 33, 32, 32, and 32 for the MET/CBT + CM, DC + CM, MET/CBT without CM, and DC without CM groups, respectively.

^cN = 132, ns = 33, 33, 33, and 33 for the MET/CBT + CM, DC + CM, MET/CBT without CM, and DC without CM groups, respectively.

^*p < .05.