Internal consistency of a diagnostic interview for children: the Child Assessment Schedule.

The purpose of this study was to evaluate the internal consistency of the content scales of the Child Assessment Schedule (CAS). A total of 116 psychiatric patients with a mean age of 10 years were administered the interview, and 92 parents were administered the parent version. Coefficient alpha was calculated for each of the 11 content scales. High internal consistency was demonstrated for school, friends, worries, mood, physical complaints, and expression of anger. More moderate but acceptable alphas were observed for the family, fears, and self-image scales. The same general pattern of results was observed for both the child and parent interviews. Additional analyses revealed that the number of items in the CAS could be reduced up to 30% without sacrificing internal consistency. These results indicate that 9 of the scales yield reliable scores.