1. Using General Growth Mixture Modeling to Study the
First Year of College Student Drinking
Greenbaum, P. E., Del Boca, F. K., Darkes, J., and
Goldman, M. S.
Alcohol and Substance Use Research Institute
Funded by NIAAA R37AA , “Alcohol Expectancies: Mediators of Biopsychological Risk,” (PI: Mark S. Goldman).

2. Background
Prior research has documented heavy drinking on college campuses (e.g., 29% were drunk 3 or more times in past month; 44% were binge drinkers, Wechsler et al., 2000).
During this period, many individuals experience their personal peak consumption and individual drinking trajectories begin to diverge; some individuals continue to increase their drinking, while others asymptote or decline (Muthén & Muthén, 2000; Schulenberg et al., 1996).
Little attention has been given to drinking changes that occur during the academic year or to factors that are associated with these temporal changes.

3. Method Sample : · 308 freshmen recruited in three successive years.
·       308 freshmen recruited in three successive years.
·    Randomly selected.
·    Abstinent participants were omitted, N = 229.
·    Sample characteristics.
Males-- 47%
Age range years (M = 18.4, SD = 0.47)
Caucasian, 71%; African American, 12%; Hispanic, 8%; Other, 8%

4. Method
Procedure :
·       Alcohol consumption was measured at eight times during the academic year using the Timeline Follow-Back interview (Sobell & Sobell, 1992).
·       Daily drinking measures were aggregated to provide weekly estimates (t = 32).
·      Risk factor variables in the current analyses, obtained at the beginning of the study, included:  
Gender
Sensation-seeking
Alcohol expectancies
Living arrangement (off-campus/home, dorm)
Ethnicity/race

5. Figure 1.
Alcohol Consumption During the First Year of College

6. Alcohol Consumption During the First Year of College
Figure 2.
Alcohol Consumption During the First Year of College
Mean Log Drinks

7. Table 1
Selecting the Baseline Latent Growth Curve Model: Likelihood Ratio Tests
Note. a Fixed effect for the slope growth factor not significant at p < bHoliday loadings were freely estimated. cCorrelated errors for weeks 1 to 4.
* p < .001

8. Selecting the Baseline Latent Growth Curve Model: Fit Indices
Table 2
Selecting the Baseline Latent Growth Curve Model: Fit Indices
Note. a Fixed effect for the slope growth factor not significant at p < .05. bHoliday loadings were fixed to cHoliday loadings were freely estimated.

9. Latent Growth Curve Model
Figure 3.
Latent Growth Curve Model
Mean Log Drinks
(100%)

10. Figure 4. 5 Class Solution Log Mean Drinks/Week (8%) (10%) (20%) (54%)
(7%)

11. Predictors of Latent Class Membership
Table 3
Predictors of Latent Class Membership
Note: Within a column, significant mean differences (p < .05) between classes are noted by different
superscripted letters.