Table 2. Correlation between the three variables for three data sets and the category of the effect size (in brackets).

R represents Spearman rank correlation, and p-values correspond to the null hypothesis that the two variables are independent. Effect size estimates are based on the size of the correlation observed between two variables, where small, medium, and large correlation thresholds are respectively 0.10, 0.30, and 0.50 based on Cohen’s classification [48].

	Gender/DAT1 and Inattention	Gender/DAT1 and Hyperactivity/Impulsivity	Inattention and Hyperactivity/Impulsivity
NeuroIMAGE	R = 0.187, p<0.001 (small)	R = 0.141, p<0.001(small)	R = 0.759, p<0.001 (large)
ADHD-200	R = 0.288, p<0.001 (small)	R = 0.215, p = 0.001 (small)	R = 0.679, p<0.001 (large)
IMpACT	R = 0.307, p = 0.001 (medium)	R = 0.224, p = 0.004 (small)	R = 0.764, p<0.001 (large)