Psychometric properties of the Strengths and Difficulties Questionnaire in an Icelandic community sample

Purpose: The current paper aimed to evaluate the psychometric properties of the Icelandic translation of the Strengths and Difficulties Questionnaire, for both parent and teacher reports. SDQ is a widely used questionnaire for screening mental problems among youth. However, only a few studies have conducted a factor analysis on the youngest and oldest cohorts using an adequate sample size. This study aims not only to examine the traditional 5-factor model and alternative models suggested in prior research but also to establish norm data for the Icelandic population. Materials and methods: The total sample consists of 1653 youth aged 5–16 years, thereof 316 parent reports and 271 teacher reports for the 5-year-old sample. We used confirmatory factor analysis to evaluate the factor structure. Special attention was given to the models’ performance across different age groups and between genders. This cross-demographic evaluation is vital to ensure that the SDQ’s utility is not limited by developmental or gender-specific variations in symptom expression or reporting. Results: We found an acceptable fit for both the original five-factor model and the more recent three-factor model with higher-order internalizing and externalizing factors. The fit for the factor structures seemed to be quite similar across ages. However, we observed goodness-of-fit below the acceptable range for girls on the parent ratings. We also found evidence for the convergent and divergent validity of both models. Conclusions: The current study provides further evidence of the utility of the SDQ as a screening instrument, with an acceptable factor structure across ages.