Activity measurements support dimensional assessment.

The Diagnostic and Statistical Manual approach to motor excess has been to treat it as a categorical variable whose presence functions as an inclusion criterion. Motor excess is thought to occur primarily during structured settings that maximize attentional demands. Activity is rarely measured as a dimensional attribute despite availability of a wide variety of suitable instruments for more than a decade (Tryon, 1985). The present study measured activity using electronic step counters in structured and unstructured school settings, commuting from home to school and back home, and at home for 2 consecutive weeks in 60 children selected from 450 children using Factor IV (hyperactivity) scores from the Conners Teacher Rating Scale to represent three levels of hyperactivity. Results indicate that (a) children rated as hyperactive are measurably more active than children rated as normally active in unstructured as well as structured situations, (b) measured activity correlates consistently and substantially with rated activity in unstructured and structured situations, and (c) a single activity factor characterizes measured activity in all situations except for class transitions during school. These results and other published findings support a quantitative (dimensional) rather than qualitative (categorical) approach to motor excess.