The psychometric properties of the Strengths and Difficulties Questionnaire in a multi-ethnic sample of young children

Objectives: Developed countries are becoming more multi-ethnic, with consequent problems of maintaining invariance of health questionnaires. We aimed to explore commonalities in the structure of the Strengths and Difficulties Questionnaire (SDQ) completed for young children in a multi-ethnic English cohort while examining potential method effects and misfitting items. The secondary aim was to demonstrate the usefulness of bifactor modelling and exploratory structural equation modelling (ESEM) for kinanthropological research. Methods: We used SDQ data from 3,290 children enrolled in the Born in Bradford cohort, completed by parents (usually the mother) at child age 3 and 4 and teachers at age 5. The factor structure for 11 potential configurations was assessed in each age group using confirmatory factor analysis. ESEM was used to assess misfitting items under the best fitting configuration. Results: The best fitting configuration was a bifactor model of the 2 broader scales and a methods factor, using the 20 difficulties items. Generally, factor loadings increased between age 3 and age 5. Several items contributed to misfit. Conclusions: There was less support for the robustness and hypothesised structure of the SDQ in this sample. Bifactor scores that account for measurement error could be useful if carefully applied in epidemiological and kinanthropological studies in multi-ethnic and/or younger age samples.