Table 2.

Prevalence rates of past month smoking stages and transition rates between past month smoking stages by age of smoking initiation

Early initiators (n = 340)						Late initiators (n = 272)
Prevalence rate			Transition rate			Prevalence rate			Transition rate
			Non	LI	Heavy				Non	LI	Heavy
			F1 stage						F1 stage
12th-grade stage	0.40	Non	0.81	0.12	0.07	12th-grade stage	0.58	Non	0.79	0.20	0.01
	0.26	LI	0.22	0.55	0.24		0.32	LI	0.24	0.57	0.19
	0.34	Heavy	0.09	0.06	0.85		0.10	Heavy	0.17	0.15	0.69
			S1 stage						S1 stage
F1 stage	0.41	Non	0.88	0.11	0.02	F1 stage	0.55	Non	0.74	0.24	0.02
	0.21	LI	0.16	0.71	0.14		0.31	LI	0.16	0.72	0.12
	0.38	Heavy	0.03	0.07	0.90		0.13	Heavy	0.08	0.10	0.82
			F2 stage						F2 stage
S1 stage	0.41	Non	0.75	0.17	0.07	S1 stage	0.47	Non	0.81	0.15	0.04
	0.22	LI	0.22	0.52	0.26		0.37	LI	0.23	0.61	0.15
	0.38	Heavy	0.06	0.18	0.76		0.16	Heavy	0.02	0.19	0.78
			S2 stage						S2 stage
F2 stage	0.38	Non	0.76	0.22	0.02	F2 stage	0.47	Non	0.85	0.15	0.00
	0.25	LI	0.27	0.47	0.26		0.33	LI	0.26	0.63	0.10
	0.37	Heavy	0.05	0.07	0.88		0.20	Heavy	0.06	0.15	0.79
			Overall transition ratea from 12th grade to S2						Overall transition ratea from 12th grade to S2
S2 stage	0.37	Non	0.68	0.22	0.09	S2 stage	0.50	Non	0.68	0.24	0.09
	0.23	LI	0.30	0.39	0.31		0.31	LI	0.28	0.52	0.20
	0.40	Heavy	0.08	0.12	0.81		0.19	Heavy	0.18	0.09	0.73

Note. F1, first fall after high school; S1, first spring after high school; F2, second fall after high school; S2, second spring after high school; non, nonsmokers; LI, light and intermittent smokers; and heavy, heavy smokers.

^aOverall transition rates are the probabilities of smoking stage membership in S2 conditional on smoking stage membership in 12th grade. They are not the proportion of participants who were non, LI, or heavy smokers throughout the course of the study.