Sex differences in gray matter volume: how many and how large are they really?

Table 1 Demographic characteristics of the participants included in the main sample and in the different subsamples used in the present study

	Main sample		Only-females		Only-males		TIV-matched
	Males	Females	Large TIV	Small TIV	Large TIV	Small TIV	Males	Females
N	185	171	74	74	74	74	74	74
AGE (years)
Mean (SD)	22.39 (3.04)	21.64 (4.90)	21.08 (2.76)	20.62 (2.98)	22.54 (3.05)	22.11 (3.13)	22.28 (2.97)	21.50 (2.71)
Range	18–30	18–49	18–30	18–30	18–30	18–30	18–30	18–31
Mean difference	0.75		0.46		0.43		0.78
95% CI	[− 0.09, 1.59]		[− 0.47, 1.39]		[−0.57, 1.43]		[− 0.14, 1.70]
Cohen’s d [95%CI]	0.18 [− 0.02, 0.39]		0.16 [− 0.16, 0.48]		0.14 [− 0.18, 0.46]		0.27 [− 0.05, 0.60]
t test	t₃₅₄ = 1.75, p = 0.08		t₁₄₆ = 0.45, p = 0.27		t₁₄₆ = 0.85, p = 0.39		t₁₄₆ = 1.68, p = 0.10
Levene’s test	F = 1.00, p = 0.36		F = 0.57, p = 0.45		F = 0.06, p = 0.85		F = 0.79, p = 0.37
Education (years)
Mean (SD)	14.61 (2.21)	14.56 (2.10)	14.61 (1.95)	14.61 (1.94)	14.69 (1.99)	14.55 (2.26)	14.69 (2.28)	14.62 (1.87)
Range	8–20	8–19	10–19	8–19	11–18	8–19	8–19	12–19
Mean difference	0.05		0.00		0.14		0.07
95% CI	[− 0.40, 0.50]		[− 0.63, 0.63]		[− 0.55, 0.83]		[− 0.61, 0.75]
Cohen’s d [95%CI]	0.02 [− 0.18, 0.23]		0.00 [− 0.32, 0.32]		0.06 [− 0.26, 0.39]		0.03 [− 0.29, 0.36]
t test	t₃₅₄ = 0.24, p = 0.81		t₁₄₆ = 0.00, p = 1		t₁₄₆ = 0.39, p = 0.70		t₁₄₆ = 0.19, p = 0.84
Levene’s test	F = 2.24, p = 0.13		F = 0.21, p = 0.65		F = 0.23, p = 0.63		F = 2.59, p = 0.11

No statistically significant differences (p < 0.05) were observed for the age means (t tests) or variances (Levene’s test) of the compared groups in the main sample or in any of the criterial subsamples

ISSN: 2042-6410