Table 4. Single Degree of Freedom Main Effect Contrasts and Standardized Effect Size Estimates (d) for Concurrent Age-18 Personality and Age-18 Substance Use Groups.

Age-18 Personality	Parameter	Standard Error	t Value	p Value	Effect Size	Lower Limit	Upper Limit
Positive emotionality
Abs-Exp	.551	1.05	.52	.601	.053	−.147	.254
Exp-PU	.951	.905	1.05	.293	.092	−.080	.264
Positive emotionality— Agentic (females)
Abs-Exp	6.242	1.566	3.99	<.001	.535	.272	.797
Exp-PU	3.360	1.434	2.34	.019	.288	.047	.528
Positive emotionality— Agentic (males)
Abs-Exp	2.276	1.661	1.37	.171	.210	−.090	.511
Exp-PU	−.072	1.326	−.05	.957	−.007	−.247	.233
Positive emotionality— Communal
Abs-Exp	−5.353	1.188	−4.50	<.001	−.443	−.636	−.250
Exp-PU	−1.293	1.020	−1.27	.205	−.107	−.273	.059
Negative emotionality
Abs-Exp	−.875	1.085	−.81	.420	−.082	−.282	.118
Exp-PU	−.422	.93	−4.53	<.001	−.396	−.568	−.225
Constraint
Abs-Exp	6.840	1.130	6.05	<.001	.600	.406	.794
Exp-PU	8.611	.970	8.88	<.001	.755	.589	.922

Note. Standardized effect size (Cohen’s d)was computed as adjusted mean of first named group minus adjusted mean of second named group divided by residual standard deviation. Except for agentic positive emotionality, covariates included in the ANCOVA models were gender, SES, and age at baseline. For agentic positive emotionality, the separate ANCOVA models for males and females only included SES and age at follow-up. Bolded values represent significant main effect contrasts following a Holm-based modified Bonferroni correction. Abs = Abstainers (age-18); Exp = Experimenters (age-18); PU = Problem Users (age-18).