Table 2. Scale Intercorrelations With 95% CI for the Full-Length Internet Addiction Test (IAT) and the 10-Item Internet Addiction Test (IAT-10).

Scale	ASRS Part A	ASRS Total1	BIS-11 Attention	BIS-11 Motor	BIS-11 Self-Control	BIS-11 Cognitive complexity	BIS-11 Perseverance	BIS-11 Cognitive instability	BIS-11 Attentional impulsivity	BIS-11 Motor impulsivity	BIS-11 Nonplanning impulsivity	PADUA COWC	PADUA DGC	PADUA CC	PADUA THSO	PADUA IHSO
Note. ASRS Part A = Adult ADHD Self-Report Scale version 1.1. Part A; ASRS Total = Adult ADHD Self-Report Scale version 1.1. Part A + Part B; BIS-11 = Barratt Impulsivity Scale 11th Edition; PADUA = Padua Inventory-Washington State University Revision; COWC = Contamination obsessions and washing compulsions subscale; DCG = Dressing/grooming compulsions subscale; CC = Checking compulsions subscale; THSO = Obsessional thoughts of harm to self/others subscale; IHSO = Obsessional impulses to harm self/others subscale. IAT = Full-Length, 20-Item Internet Addiction Test; IAT-10 = 10-Item Internet Addiction Test; n = size of participant subsample; r(x,z) = correlation of IAT with IAT-10 in subsample. Z statistic for two-tailed test (Lenhard & Lenhard, 2014). p = unadjusted probability value for the Z statistic. B-H p = probability value of the Z statistic adjusted for multiple comparisons using Benjamini–Hochberg false discovery rate (q = .05). d—Cohen’s d effect size estimate based on Z test for the difference between correlations (Lenhard & Lenhard, 2016; Rosenthal & DiMatteo, 2001). 95% CI for correlation in brackets (Lenhard & Lenhard, 2014). IAT α = .83 (SA); IAT-10 α = .80 (SA); IAT α = .85 (USA); IAT-10 α = .80 (USA). Correlations have been disattenuated to reflect the reliability of test scores in the subsamples (Spearman, 1910).
1 Data for ASRS-v1.1 Part B (Items 7–18) not collected in the USA sample.
SA
IAT	.205 [.116, .291]	.303 [.217, .384]	.067 [−.019, .152]	–.162 [−.244, −.077]	.022 [−.063, .107]	.028 [−.058, .113]	.060 [.026, .145]	–.044 [−.129, .042]	.021 [−.065, .107]	–.083 [−.168, .003]	.036 [−.050, .121]	.249 [.165, .329]	.366 [.288, .440]	.318 [.237, .395]	.312 [.230, .389]	.307 [.225, .385]
IAT-10	.293 [.207, .374]	.370 [.288, .446]	–.210 [−.291, −.127]	–.494 [−.556, −.426]	–.001 [.086, .084]	–.233 [−.312, −.150]	–.390 [−.460, −.315]	–.262 [−.340, −.180]	–.248 [−.327, −.166]	–.412 [−.481, −.338]	–.094 [−.178, −.008]	.377 [.299, .450]	.440 [.366, .508]	.490 [.420, .554]	.432 [.357, .501]	.364 [.285, .438]
n	459	458	523	525	530	523	523	523	523	523	523	501	500	497	495	493
r(x, z)	.836 [.806, .862]	.836 [.806, .862]	.841 [.814, .864]	.839 [.812, .863]	.841 [.814, .864]	.841 [.814, .864]	.841 [.814, .864]	.841 [.814, .864]	.841 [.814, .864]	.841 [.814, .864]	.841 [.814, .864]	.837 [.809, .861]	.837 [.809, .861]	.835 [.806, .860]	.832 [.803, .857]	.832 [.803, .857]
Z	–3.400	–2.666	11.307	14.444	.936	10.679	18.841	8.969	11.025	13.938	5.267	–5.303	–3.185	–7.373	–4.992	–2.324
p	<.001	.004	<.001	<.001	.175	<.001	<.001	<.001	<.001	<.001	<.001	<.001	.001	<.001	<.001	.010
B-H p	.001	.005	.001	.001	.175	.001	.001	.001	.001	.001	.001	.001	.001	.001	.001	.011
d	.322	.251	1.138	1.624	.081	1.056	2.907	.853	1.101	1.538	.473	.488	.288	.701	.461	.211
USA
IAT	.457 [.343, .558]		.382 [.267, .486]	.400 [.287, .502]	.049 [.079, .176]	.383 [.268, .487]	.580 [.488, .659]	.473 [.367, .566]	.465 [.359, .559]	.435 [.325, .533]	.180 [.054, .301]	.297 [.174, .411]	.370 [.252, .477]	.436 [.322, .538]	.385 [.266, .492]	.219 [.089, .342]
IAT-10	.424 [.306, .529]		.354 [.237.461]	.398 [.285, .500]	.115 [.013, .239]	.375 [.260, .480]	.634 [.551, .705]	.399 [.286, .501]	.414 [.302, .515]	.444 [.335, .541]	.221 [.096, .339]	.301 [.178, .415]	.421 [.298, .514]	.437 [.323, .538]	.392 [.274, .499]	.255 [.127, .375]
n	210		236	236	236	236	236	236	236	236	236	.228	.228	219	219	219
r(x, z)	.924 [.901, .942]		.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.902, .940]	.923 [.901, .940]	.923 [.901, .940]	.925 [.903, .942]	.925 [.903, .942]	.925 [.903, .942]
Z	1.363		1.175	.085	–2.577	.337	–2.677	3.216	2.22	–.392	–1.629	–.161	–2.131	–.042	–.289	–1.408
p	.086		.120	.466	.005	.368	.004	.001	.013	.348	.052	.436	.017	.483	.386	.080
B-H p	.161		.200	.483	.035	.483	.025	.015	.049	.483	.013	.483	.051	.483	.483	.161
d	.189		.153	.011	.340	.044	.354	.428	.292	.051	.213	.021	.285	.006	.039	.191