Normative data for the self‑reported and parent‑reported Strengths and Difficulties Questionnaire (SDQ) for ages 12–17

Background: The Strengths and Difficulties Questionnaire (SDQ) is widely used to screen for psychosocial problems among adolescents. As the severity of such problems is known to be related to age and gender, screening could be improved by interpreting SDQ scale scores with age-specific and perhaps gender-specific norms. Up to now, such norms are lacking. The aim of the current study is to present gender-specific and joint normative data per year of age for the Dutch self-reported and parent-reported SDQ versions for use among 12- to 17-year-old adolescents. Methods: The norm groups for the self-reported and parent-reported SDQ versions consisted of 993 adolescents and 736 parents, respectively, from the general Dutch population. Per SDQ version, both gender-specific norms and joint norms (percentiles and cutoffs) per year of age were calculated through regression-based norming (Rigby in J Roy Stat Soc Ser C 54:507, 2005). Additionally, these norms were compared to the widely used British norms that are neither age-specific nor gender-specific. Results: By design, gender-specific ‘abnormal’ cutoffs (i.e., cutoffs aimed at identifying max. 10% of the most extremely scoring males and max. 10% of the most extremely scoring females) resulted in about equal percentages of ‘abnormal’ scoring male and female adolescents per SDQ scale. In contrast, joint ‘abnormal’ cutoffs (i.e., cutoffs aimed at identifying max. 10% of the most extremely scoring adolescents) resulted in relatively more male (7.6 to 13.6%, depending on age) than female (3.3 to 8.9%, depending on age) adolescents as scoring ‘abnormal’ on scales measuring externalizing behavior (self-reported and parent-reported SDQ versions), and relatively more female (3.9 to 14.3%, depending on age) than male (1.8 to 6.9%, depending on age) adolescents as scoring ‘abnormal’ on scales measuring internalizing behavior (self-reported SDQ version). In both types of norms, minor age effects were present. Among Dutch adolescents, the British norms yielded detection rates much lower than the expected 10%.
Conclusions: Our findings indicate that detection rates depend on the reference group that is used (British or Dutch general adolescent population; specific gender group or not). The normative data in this paper facilitate the comparison of an adolescent’s scores to different reference groups, and allow for cross-country/cultural comparisons of adolescents’ psychosocial behavior.