Table 2:

Descriptive Statistics and Missing Data

	n (% missing)a	Mechanisms of missingness	M	SD	Skewness	SE	Kurtosis	SE
BRIEF - Parent
EC	139 (5.44)	Non-compliance, experimenter error	56.21	14.66	0.49	0.21	−0.67	0.41
BRI	139 (5.44)		57.79	15.71	0.57	0.21	−0.49	0.41
MI	139 (5.44)		57.01	12.36	0.17	0.21	−0.67	0.41
GEC	139 (5.44)		57.97	13.97	0.30	0.21	0.71	0.41
BRIEF - Youth
EC	135 (8.16)	Non-compliance, experimenter error	51.94	11.80	0.62	0.21	−0.29	0.41
BRI	136 (7.48)		50.54	12.41	0.40	0.21	−0.53	0.41
MI	136 (7.48)		50.42	11.57	0.26	0.21	−0.67	0.41
GEC	136 (7.48)		50.54	12.33	0.30	0.21	−0.61	0.41
D-KEFS
VS	139 (5.44)	Non-compliance, experimenter error	10.34	2.93	−0.92	0.21	0.93	0.41
NS	139 (5.44)		10.53	3.17	−1.38	0.21	1.63	0.41
LS	139 (5.44)		10.22	3.46	−1.40	0.21	1.54	0.41
N-LS	138 (6.12)		9.24	3.68	−1.03	0.21	0.42	0.41
TAS	137 (6.80)		10.45	3.35	−1.55	0.21	3.28	0.41
Stop Signal Task
SSRT	123 (16.32)	Non-compliance, invalid responding	247.58	117.11	0.97	0.22	−0.46	0.41
Self-Reported Frustration (Go/No-Go)
Baseline	260 (3.35)		2.02	0.97	1.03	0.15	0.95	0.30
Frustration	259 (3.72)	Non-compliance	3.28	1.27	−0.11	0.15	−1.08	0.30
Recovery	258 (4.09)		1.93	1.03	1.25	0.15	1.31	0.30
% Accuracy (Go/No-Go)
Baseline	245 (8.92)	Non-compliance, technological malfunction	67.95	6.85	−2.19	0.16	10.63	0.31
Frustration	245 (8.92)		56.97	4.80	−0.16	0.16	2.49	0.31
Recovery	243 (9.67)		69.22	6.56	−1.14	0.16	6.38	0.31
RSA (Go/No-Go)
Baseline	227 (15.61)	Non-compliance, technological malfunction, excessive movement	75.13	39.13	1.30	0.16	2.56	0.32
Frustration	224 (16.73)		76.87	41.58	1.73	0.16	4.60	0.32
Recovery	225 (16.35)		73.70	41.58	1.67	0.16	3.64	0.32
PEP (Go/No-Go)
Baseline	226 (15.99)	Non-compliance, technological malfunction, excessive movement	53.91	31.04	0.34	0.16	<-0.01	0.32
Frustration	224 (16.73)		56.02	34.29	0.84	0.16	2.89	0.32
Recovery	222 (17.47)		54.88	30.26	0.13	0.16	−0.64	0.33

^aThese missing data were treated as missing at random and estimated in MPlus using Maximum Likelihood model.