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

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

  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
  1. 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