The SKAMP scale measured the manifestations of attention deficit hyperactivity disorder (ADHD) using an independent observer rating of the participant's impairment in classroom observed behaviors. SKAMP combined score comprised of 13 items (including subscales: attention with items 1-4, deportment with items 5-8, quality of work with items 9-11 and compliance with items 12-13). The SKAMP composite score was obtained by summing up each item score where each item was rated on a 7-point impairment scale (0=normal to 6=maximal impairment) for a total possible combined score of 0 to 78; where higher score signified worst impairment. Average of all post dose SKAMP-combined scores measured at 0.75, 2, 4, 8, 10, 12 and 13 hours post-dose was calculated.