. Author manuscript; available in PMC: 2018 Jun 1.

Published in final edited form as: Dev Cogn Neurosci. 2017 Feb 1;25:58–68. doi: 10.1016/j.dcn.2017.01.011

Table 2. Descriptive statistics for the first scan session.

Group	Mean frames analyzed	Mean FD (mm)	FD skew	Mean frames analyzed after scrubbing	Mean FD (mm) after scrubbing	FD skew after scrubbing	Proportion with ADHD data	Mean ADHD severity rating
Twins	931.05 [215.30]	.63 [.63]	2.48	717.70 [243.54]	.20 [.08]	.52	.95	11.70^a [9.97]
Nonstruggling readers	1298.66 [131.52]	.50 [.42]	1.92	1051.32 [216.62]	.19 [.06]	.08	.34	-15.00^b [12.16]
Struggling readers	1207.59 [273.53]	.62 [.56]	2.03	939.12 [295.47]	.20 [.07]	.53	.82	.58^b [17.20]

Note. Descriptive statistics for number of frames analyzed, session-wide framewise displacement (FD) in millimeters before and after motion scrubbing, and attention deficit hyperactivity disorder (ADHD) ratings. Standard deviations are in brackets.

ADHD ratings correspond to the sum of inattentive and hyperactive-impulsive item scores from the Conners' rating scales.

ADHD ratings correspond to the sum of inattentive and hyperactive-impulsive item scores and SWAN rating scales.