The reliability and validity of the Questionnaire - Children with Difficulties (QCD)

BACKGROUND The aim of this study was to evaluate the reliability and validity of the Questionnaire-Children with Difficulties (QCD), which was developed for the evaluation of children's daily life behaviors during specified periods of the day. METHODS The subjects were 1,514 Japanese public elementary and junior high school students. For the examination of reliability, Cronbach's alpha was calculated to assess the internal consistency of the questionnaire. With regard to validity, correlation coefficients were calculated to examine whether QCD scores correlated with those of the ADHD-Rating Scale (ADHD-RS) and the Oppositional Defiant Behavior Inventory (ODBI). RESULTS Cronbach's alpha coefficient for the total score of the QCD was .876. The correlation coefficients of the QCD score with ADHD-RS and ODBI scores were -.514 and -.577, respectively. CONCLUSIONS The internal consistency and validity of the QCD were demonstrated. The QCD is a reliable and valid instrument for evaluating daily life problems for children during different time periods of the day.