Source	Sample	GMA measure	Correlation
Willerman, Schultz, Rutledge and Bigler (1991)	20 European-American male university students with mean age = 18 years	WAIS-R	0.51
Willerman et al. (1991)	20 European-American female university students with mean age = 18 years	WAIS-R	0.33
Andreasen et al. (1993)	37 European-American males aged 18–75 years	WAIS-R	0.40
Andreasen et al. (1993)	30 European-American females aged 18–75 years	WAIS-R	0.44
Raz et al. (1993)	29 European-Americans (17 men, 12 women) with mean age = 43.8 years (SD = 21.5)	CFIT	0.43
Egan et al. (1994; corrected by Egan, Wickett, & Vernon, 1995)	40 British military (unreported sex and race breakdown) with mean age = 23 (SD = 5), corrected for height, weight, and restricted range	WAIS-R	0.48
Castellanos et al. (1994)	46 children aged 5–19 years of unknown background	WISC-R subscales	0.33
Harvey, Persaud, Ron, Baker, and Murray (1994)	34 healthy male and female British hospital staff and locals (62% Caucasian; 38% Afro-Caribbean) used as control group	NART	0.69
Jones et al. (1994)	67 healthy male and female British, aged 16–60 years, some Afro-Caribbean, used as a community control group	NAT or verbal subtest of the WAIS	0.30
Wickett et al. (1994)	40 White Canadian women aged 20–30 years; height and weight partialed out and corrected for restriction of range	MAB	0.40
Kareken et al. (1995)	68 Caucasian and non-Caucasian adults of both sexes aged 18–45 years	Average of various subtests	0.25
Reiss, Abrams, Singer, Ross, and Denckla (1996)	12 boys, mainly White, aged 5–17 years	WISC-R	0.52
Reiss et al. (1996)	57 girls, mainly White, aged 5–17 years	WISC-R	0.37
Flashman, Andreasen, Flaum, and Swayze (1998)	90 healthy normal volunteer controls (47% female) with mean age = 27 years (SD = 10)	WAIS-R	0.25
Tramo et al. (1998)	20 individuals (10 pairs of identical twins) aged 24–43 years; we use their total cortical surface area as the estimate of brain size	WAIS-R	0.20
Gur et al. (1999)	40 men with a mean age = 26 years (SD = 5.5)	Various	0.40
Gur et al. (1999)	40 women with a mean age = 26 years (SD = 5.5)	Various	0.39
Tan et al. (1999)	54 female university students in Turkey, aged 18–26 years	CFIT	0.62
Tan et al. (1999)	49 male university students in Turkey, aged 18–26 years	CFIT	0.28
Wickett et al. (2000)	68 individuals (34 pairs of brothers) aged 20–35 years	g, from MAB and other tests	0.38
Pennington et al. (2000)	96 individuals (48 pairs of MZ and DZ twins), mean age = 17 years (SD = 4.1)	WISC-R and WAIS-R	0.42
Pennington et al. (2000)	36 individuals (18 pairs of MZ and DZ twins), mean age = 19 years (SD = 3.7)	WISC-R and WAIS-R	0.31
Schoenemann, Budinger, Sarich, and Wang (2000)	72 individuals (36 pairs of sisters) aged 18–43 years	g, from 11 diverse cognitive tasks including Raven's Matrices with corrections for age	0.45
Aylward et al. (2002)	83 White men and women aged 8–46 years used as healthy controls	Unspecified IQ test	0.04
MacLullich et al. (2002)	97 healthy men aged 68 years (SD = 1.3)	g, from various tests including NART and Raven's Matrices	0.42
Ivanovic et al. (2004)	47 male 18-year-old high school students in Chile selected from the richest and poorest counties	WAIS-R	0.55
Ivanovic et al. (2004)	49 female 18-year-old high school students in Chile selected from the richest and poorest counties	WAIS-R	0.37
Deary et al. (2007)	48 male 71- to 76-year-olds resident in Scotland	NART	0.56
Number of samples: 28
Total N: 1,389
Unweighted mean r = 0.40
N-weighted mean r = 0.38

Note. CFIT, Culture-Free Intelligence Test; MAB, Multidimensional Aptitude Battery; MRI, Magnetic Resonance Imaging; NART, New Adult Reading Test; PMAT, Primary Mental Abilities Test; WAIS-R, Wechsler Adult Intelligence Scale-Revised; WISC, Wechsler Intelligence Scale for Children.