The unconditional LGCM for alcohol use in the total sample fit the data well: χ2 [3] =2.83, p=.42; CFI=1.00; TLI=1.00; and RMSEA<.001. The LGCM had a significant mean slope, Ms=.18, z=7.15, p<.001, confirming that there was significant growth in propensity for alcohol use across early adolescence. The Ms value of 0.18 can be interpreted as the increase in proportion of alcohol users per year (0.18×3 [T15 - T12]=.54), which corresponds to a 54% increase in the proportion of users across ages 12 to 15 years. The variances for the intercept and slope were Di=0.65, z=6.41, p<.001 and Ds=.08, z=3.13, p<.01 respectively, indicating substantial variation across girls in both initial use and trajectory of use. Initial levels of alcohol use were negatively associated with propensity to use alcohol over time (b=−.09, z=−2.05, p=.04). A linear slope fit the data best; when testing a quadratic trend in slope, the model failed to converge.
