Scale properties of the Japanese version of the Strengths and Difficulties Questionnaire (SDQ): A study of infant and school children in community samples

The Strengths and Difficulties Questionnaire (SDQ) is a short screening instrument which addresses the positive and negative behavioral attributes of infants, children and adolescents. The SDQ is widely used to evaluate child developmental disabilities, psychological and psychiatric conditions or disorders in Japan. However, we did not have normative data for the Japanese version until now. To establish the community-based data and properties for the Japanese version, we collected and evaluated parent ratings of a total of 2899 Japanese children aged 4-12 years, including 1463 boys and 1436 girls. Statistical evaluation of psychometric properties included a factor analysis verifying the proposed scale structure, an assessment of scale homogeneities, and the determination of age, gender and relationship of each difficulties scale, or prosocial scale. The total difficulties score in boys (8.70 +/- 5.03) was higher than in girls (7.86 +/- 4.88). Based on the distributions of SDQ scores observed in the Japanese community sample, recommended bandings identifying normal, borderline, and abnormal (clinical ranges) were defined for each scale, and some gender difference was found in some difficulties and prosocial SDQ scores. After evaluating parent ratings obtained in a community-based sample, the Japanese SDQ was shown to possess favorable psychometric properties. Thus, the Japanese translation of this popular and versatile instrument seems to be approximately as reliable and useful as the original English questionnaire.