. Author manuscript; available in PMC: 2015 May 13.

Published in final edited form as: Psychol Med. 2014 Feb 20;44(13):2867–2876. doi: 10.1017/S0033291714000269

Table 1.

Demographic and clinical characteristics of the NTR sample, for the twin sample and for relatives of twins. Individuals who were missing data for both the HRS-SR and PI-ABBR were excluded (N = 906). N with available HRS-SR data = 15,429. N with available PI-ABBR data = 15,258. N with both HRS-SR and PI-ABBR data = 14,773.

	Total sample N = 15,914	Twin sample N = 7,906	Relative sample N = 8,008	X² or t, p value
Percent male (N)	35.9% (5,719)	30.6% (2,418)	41.2% (3,301)	195.5, p<0.0001
Mean age (SD)	41.3 (16.0)	33.2 (14.5)	49.2 (13.1)	72.9, p<0.00001
Mean HRS-SR (SD)	6.2 (5.8)	5.7 (5.6)	6.7 (6.1)	10.6, p<0.00001
Mean PI-ABBR (SD)	6.7 (4.9)	6.9 (5.2)	6.4 (4.7)	−6.3, p<0.00001