Table 4.

Parameter Estimates for LTA Model

		Non-users	Smokers	Moderate Drinkers/ Smokers	CCH Users
		Latent Class Membership Probabilities
Time 1		0.309	0.277	0.196	0.218
Time 2		0.309	0.268	0.184	0.239
		Item Response Probabilities
Tobacco	No use	0.973	0.045	0.260	0.161
	Less than a pack a day	0.027	0.668	0.571	0.414
	Pack a day or more	0.000	0.287	0.168	0.426
Alcohol	No use	0.654	0.866	0.000	0.211
	Less than 3–4 days a week	0.323	0.116	0.863	0.454
	3–4 days a week or more	0.024	0.018	0.137	0.335
Marijuana	No use	0.946	0.862	0.548	0.529
	Less than once a week	0.040	0.079	0.244	0.218
	Once a week or more	0.014	0.059	0.208	0.253
Crack, Cocaine	No use	0.988	0.932	0.969	0.122
or Heroin	Less than once a week	0.012	0.056	0.031	0.271
	Once a week or more	0.000	0.012	0.000	0.606
Other Drugs	No use	0.992	0.992	0.865	0.871
	Some use	0.009	0.008	0.135	0.129
		Transition Probabilities
		Time 2 Latent Class Membership
Time 1 Latent Class Membership		Non-users	Smokers	Moderate Drinkers/ Smokers	CCH Users
Non-users		0.998	0.000	0.000	0.002
Smokers		0.000	0.900	0.000	0.100
Moderate Drinkers/Smokers		0.000	0.095	0.905	0.000
CCH Users		0.000	0.000	0.030	0.970

Note: CCH is crack, cocaine or heroin.