0, 1, and 2, respectively, for each of the 5 items. These were summed together at each age. Where 3 or more items were missing, the sum score for that age was not calculated; if 1 or 2 items were missing, the available items were pro-rated. Skewness for sum scores ranged from 1.24–1.48; kurtosis ranged from 1.30–2.29; Cronbach’s alpha ranged from 0.75–0.82.
