. Author manuscript; available in PMC: 2013 Mar 13.

Published in final edited form as: Twin Res Hum Genet. 2010 Dec;13(6):550–558. doi: 10.1375/twin.13.6.550

Table 3.

Mediation Models for Aggressiveness: Regression Coefficients (β) and Odds Ratios (OR) with 95% Confidence Intervals in Parentheses

Aggressiveness	Direct effect: Aggressiveness → Drug use		Aggressiveness → Smoking		Smoking → Drug use		Indirect effect: Aggressiveness → Drug use
Boys (n = 1992)	β_dt/β_dp	OR	β_st/β_sp	OR	β_ds	OR	β_st/β_sp ^* β_ds	OR

Teacher ratings	0.30 (0.08, 0.53)	1.35 (1.08, 1.69)	0.61 (0.44, 0.79)	1.85 (1.56, 2.19)	1.73 (1.38, 2.08)	5.65 (3.99, 8.00)	1.06 (0.70, 1.43)	2.90 (1.83, 3.97)
	(p = .008)		(p < .001)		(p < .001)		(p < .001)
Parental ratings	0.28 (−0.09, 0.64)	1.32 (0.92, 1.90)	0.74 (0.49, 0.99)	2.09 (1.63, 2.68)	1.78 (1.43, 2.12)	5.91 (4.20, 8.32)	1.31 (0.79, 1.83)	3.71 (1.77, 5.64)
	(p= .135)		(p < .001)		(p < .001)		(p < .001)

Girls (n = 2123)	β_dt/β_dp	OR	β_st/β_sp	OR	β_ds	OR	β_st/β_sp ^* β_ds	OR

Teacher ratings	0.29 (0.05, 0.30)	1.35 (1.05, 1.72)	0.98 (0.75, 1.21)	2.65 (2.11, 3.34)	1.78 (1.45, 2.11)	5.92 (4.27, 8.21)	1.74 (1.22, 2.53)	5.67 (2.73, 8.61)
	(p = .017)		(p < .001)		(p < .001)		(p < .001)
Parental ratings	0.57 (0.24, 0.90)	1.72 (1.27, 2.47)	0.84 (0.57, 0.84)	2.32 (1.74, 3.04)	1.80 (1.47, 2.12)	6.02 (4.37, 8.30)	1.51 (0.96, 2.07)	4.55 (2.01, 7.71)
	(p = .001)		(p < .001)		(p < .001)		(p < .001)