The Strengths and Difficulties Questionnaire as a screening instrument in a community sample of high school seniors in Sweden.

The Strengths and Difficulties Questionnaire (SDQ) has been used among Swedish children since 1996, usually the parent or the teacher version. The self-report version was originally developed for children aged 11-16 years. The aim of this study was to investigate the application of the Swedish self-report version to a representative sample of 1015 senior high school students aged 17-19 years. Girls reported more emotional symptoms and scored higher on prosocial items than boys. Boys on the other hand scored higher on both conduct and peer problems. The means were similar to means in two Nordic studies that have included subjects of this age group. A confirmatory five-factor analyses explained 44.5% of the variance with a good fit for all subjects and boys but somewhat weaker for girls. The item-subscale correlation (ISC) ranged from moderate to high (r=0.47-0.76) and the Cronbach's alpha was 0.74 (ranging in the five subscales 0.50-0.70). The SDQ seems to be useful even in this older age group. The psychometric qualities were acceptable but can probably be improved by changing the oppositely worded questions and by considering development of different questionnaires for boys and girls at least in late adolescence.