g., low-increasing from low-stable) LB42708? or converged toward a similar smoking pattern by Y4 (e.g., high-decreasing and low-stable). Figure 1. Trajectories of cigarette smoking during 4 years of college (n = 1,253). Means and SE bars of number of smoking days in the past month depicted at each timepoint. The percentages shown in the figure are unweighted. After statistically weighting the sample … BIC values, parameter estimates, and probabilities of trajectory group membership are available as Supplementary Tables 1�C3. In summary, significant changes in smoking frequency occurred within all but the stable nonsmokers. Mean probability of membership in each of the five groups ranged from .91 to .99.

Pairwise comparisons of trajectory slopes indicated that the trajectory shapes were significantly different from each other, with the exception that the stable nonsmokers�� trajectory shape was not significantly different from that of the low-stable or high-stable groups (results available upon request). Comparisons of Smoking Trajectory Group Means Between-group comparisons of smoking trajectory intercepts at Y1 and Y4 illustrate the divergence and convergence of certain trajectories. High-decreasers initially (Y1) smoked somewhat less than high-stable smokers (Figure 1; 14.3 vs. 18.2, p < .001), but by Y4, they were smoking only slightly more than the low-stable group (2.6 vs. 1.7, p < .001). Conversely, low-increasers initially (Y1) smoked no more frequently than the low-stable group (1.3 vs. 1.2 days, p = .44) and subsequently diverged, yet never approached the high-stable mean, even in Y4 (15.

5 vs. 23.8, p < .001). All remaining comparisons were statistically significant at p < .003. Comparison of Y1 Characteristics of Smoking Trajectory Groups Bivariate comparisons revealed significant differences between smoking trajectory groups on both demographic and Y1 substance use characteristics (Table 1). Both males and Whites were slightly over-represented in all four smoking trajectory groups (relative to stable nonsmokers). No differences in age or neighborhood income were observed. Stable nonsmokers also had less alcohol involvement as measured by past-year drinking, typical alcohol consumption, and alcohol dependence, although some comparisons did not achieve statistical significance. Comparing the low-stable and low-increasing groups, Y1 smoking patterns were similar in terms of time since first cigarette (2.7 vs. 2.9 years), past-month smoking (49.5% vs. 41.0%), number of cigarettes per day (1.5 vs. 1.5), and their alcohol involvement were also similar. The high-decreasing and high-stable groups were not significantly different, although high-stable smokers had been smoking somewhat longer (4.1 vs. 3.5 years) and more heavily Entinostat (4.7 vs. 3.