. Author manuscript; available in PMC: 2015 May 27.

Published in final edited form as: Exp Aging Res. 2009 Apr-Jun;35(2):178–201. doi: 10.1080/03610730902720372

Table 3.

Intraclass and cross-twin-cross-trait correlations for self-rated health and the cognitive scales separately by zygosity and age group (adjusted for sex and age within group).

		Intraclass Correlations		Cross Correlations with self-rated health

Age group	Scale	MZ	DZ	MZ	DZ
< 67 years old	Self-rated health	0.29 (50)^**	0.11 (93)
	Verbal ability	0.64 (51)^**	0.14 (96)^*	0.07	-0.05
	Spatial reasoning	0.74 (52)^**	0.28 (92)^**	0.13	0.08
	Perceptual speed	0.66 (50)^**	0.04 (89)	0.07	0.04
	Working memory	0.49 (52)^**	0 (96)	-0.04	0.06
	Visual memory	0.44 (49)^**	0.07 (92)	0.21^*	-0.01
≥ 67 years old	Self-rated health	0.27 (43)^*	0.23 (85)^*
	Verbal ability	0.64 (47)^**	0.06 (90)	0.15	0.05
	Spatial reasoning	0.64 (40)^**	0.28 (85)^**	0.08	0.03
	Perceptual speed	0.42 (38)^**	0.37 (71)^**	0.16	0.18^*
	Working memory	0.48 (46)^**	0.06 (88)	-0.07	-0.03
	Visual memory	0.42 (39)^*	0.30 (73)^**	0.20	0.09

Note: Number of twin pairs in parentheses.

^**

p<.01

p<.05