. Author manuscript; available in PMC: 2015 May 1.

Published in final edited form as: Psychol Med. 2013 Sep 4;44(7):1499–1509. doi: 10.1017/S0033291713002286

Table 3.

Parameter Estimates for the Best-Fitting Bivariate and Univariate G X E Models

Parameter	Bivariate Model		Univariate Model
Parameter	β (95% CI)	p	β (95% CI)	p
Common A path to Combat	.50 (.44 – .55)	< .001	N/A
Common A path to PTSD	1.26 (.84 – 1.67)	< .001	N/A
Common E path to Combat	.57 (.53 – .61)	< .001	N/A
Common E path to PTSD	.75 (.39 – 1.11)	< .001	N/A
Unique A path to PTSD	1.26 (.60 – 1.93)	< .001	1.31 (.68 – 1.93)	< .001
Unique E path for PTSD	2.92 (2.61 – 3.23)	< .001	2.93 (2.62 – 3.24)	< .001
Unique A * Combat	.75 (.22 – 1.28)	.006	.74 (.19 – 1.28)	.008
Unique E * Combat	.75 (.46 – 1.03)	< .001	.74 (.43 – 1.05)	< .001
MZ: Combat_T1 to PTSD_T1	N/A		1.59 (1.19 – 1.98)	< .001
MZ: Combat_T2 to PTSD_T1	N/A		.37 (.00 – .74)	.05
DZ: Combat_T1 to PTSD_T1	N/A		1.99 (1.37 – 2.60)	< .001
DZ: Combat_T2 to PTSD_T1	N/A		.08 (−.40 – .56)	.74

Note. All β are unstandardized coefficients. A = genetic; E = non-shared environment; PTSD = posttraumatic stress disorder; CI = confidence interval; MZ = monozygotic; DZ = dizygotic; T1 = twin 1; T2 = twin 2; N/A = not applicable.