Table 4.

Standardized Means (and Unstandardized Variances) of Slope and Intercept Factors Within the Univariate Latent Growth Models

Substance Use Outcome	Intercept mean	Slope mean	Intercept variance
Tobacco Use Frequency	0.87***	0.73***	1.42**
Tobacco Use Quantity	1.56***	1.21***	22.35***
Alcohol Use Frequency	2.68***	0.99***	0.22***
Alcohol Use Quantity	2.27***	0.78***	3.23***
Cannabis Use Frequency	0.63***	0.72***	0.39***

Notes. Slope variances are not presented as they were fixed to 1.0 for model identification. Note that although the tobacco use frequency and alcohol use quantity slope means are positive, the overall shape of change for these outcomes was quadratic, with individuals increasing and then decreasing in their use across age.

^**p<.01,

^***p<.001.