Table 2.

Summary of studies included in the meta-analysis of diffusion model parameters in ADHD

Parameter	Study	N Control	N ADHD	ES (g)	95% CI	Q	I2
Drift rate	Karalunas and Huang-Pollock (2013)	62	91	0.81	0.48–1.15
	Karalunas et al. (2012a, Cohort #1)	50	164	0.40	0.08–0.72
	Karalunas et al. (2012a, Cohort #2)	91	81	0.68	0.37–0.98
	Metin et al. (2013)	48	65	0.96	0.57–1.35
	Salum et al. (2013)	378	100	0.42	0.20–0.65
	Overall effect	629	501	0.63	0.42–0.83	8.9	55.3
Boundary separation	Karalunas and Huang-Pollock (2013)	62	91	0.21	−0.11 to 0.53
	Karalunas et al. (2012a, Cohort #1)	50	164	0.21	−0.11 to 0.52
	Karalunas et al. (2012a, Cohort #2)	91	81	−0.11	−0.41 to 0.19
	Metin et al. (2013)	48	65	−0.09	−0.46 to 0.28
	Mulder et al. (2010)	30	25	0.13	−0.40 to 0.66
	Salum et al. (2013)	378	100	−0.25	−0.47 to −0.03
	Overall effect	629	501	0.01	−0.19 to 0.16	8.7	42.3
Nondecision time	Karalunas and Huang-Pollock (2013)	62	91	−0.37	−0.04 to −0.69
	Karalunas et al. (2012a, Cohort #1)	50	164	−0.22	−0.54 to 0.09
	Karalunas et al. (2012a, Cohort #2)	91	81	−0.19	−0.49 to 0.11
	Metin et al. (2013)	48	65	−0.77	−1.55 to −0.39
	Mulder et al. (2010)	30	25	0.01	−0.52 to 0.53
	Salum et al. (2013)	378	100	−0.32	−0.54 to −0.10
	Overall effect	629	501	−0.32	−0.48 to −0.15	7.9	37.1
SDRT	Karalunas and Huang-Pollock (2013)	62	91	0.62	0.30 to 0.95
	Karalunas et al. (2012a, Cohort #1)	50	164	0.53	0.21–0.85
	Karalunas et al. (2012a, Cohort #2)	91	81	0.78	0.47–1.09
	Overall effect	203	336	0.65	0.46–0.83	1.3	0

SDRT, standard deviation of reaction time; CI, confidence interval.