Table 5.

Regression Coefficients from Latent Growth Models Predicting Intercept and Slope Factors for the Frequency and Quantity of Substance Use from the Age of Substance Use Initiation

Phenotype	Intercept	Slope
	Age of Tobacco Initiation
Tobacco Use Frequency	−0.16	−0.31***
Tobacco Use Quantity	−0.33***	0.16
Alcohol Use Frequency	−0.23***	0.25***
Alcohol Use Quantity	−0.19***	−0.15
Cannabis Use Frequency	−0.38	−0.14**
	Age of Alcohol Initiation
Tobacco Use Frequency	−0.38	−0.21**
Tobacco Use Quantity	−0.17***	0.06
Alcohol Use Frequency	−0.52***	0.14***
Alcohol Use Quantity	−0.28***	−0.13
Cannabis Use Frequency	−0.25***	0.01
	Age of Cannabis Initiation
Tobacco Use Frequency	−0.31**	−0.29**
Tobacco Use Quantity	−0.24***	0.23**
Alcohol Use Frequency	−0.38***	0.31***
Alcohol Use Quantity	−0.22***	−0.07
Cannabis Use Frequency	−0.05	−0.36

Notes. An alpha level of .008 was used to determine significance for these analyses.

^**p<.01,

^***p<.001.