Are answers affected by data collection on paper or online? The case of Belgian adolescents

Abstract Background In the early 2000s, the prevalence estimations were compared in relation with the mode of data collection, i.e. paper or online. Following the widely spread routine use of connected devices, especially in adolescents, such a monitoring is of interest. Within the 2022 “Health Behaviour in school-aged children” survey in French-speaking primary and secondary schools of Belgium, those participating could choose between paper and online collection. Our objective was to compare a large set of indicators between the two modes after adjusting for the students’ characteristics. Methods After a two-stage random selection of schools and classes, 11,751 10-to-20-year-old adolescents completed the questionnaire either on paper or online. Descriptive analysis and comparisons were conducted using chi2 and multiple logistic regressions adjusted for the students’ sociodemographic characteristics that may vary according to the questionnaire mode. Results Overall, 54.9% of the questionnaires were completed online. The choice of the collection mode provided to the schools’ headteachers was associated with the adolescents’ characteristics. Those who completed the questionnaire online were more likely to be in secondary schools, in Wallonia, and of a more favourable socioeconomic profile. After adjustments, no difference in the indicators regarding health, well-being, substance use, or sleep duration was observed. Conversely, a difference was observed for screen time (internet ≥2h/weekday: 70.4% on paper vs. 72.3% online; adjusted P-value: 0.02), some food groups (daily vegetables: 51.2% vs. 58.0%; P-value<0.001) and body weight status (overweight including obesity: 16.7% vs. 14.0%; P-value<0.001). Conclusions In some circumstances such as data collection in the school setting, mixed modes are still necessary due to operational issues. While most indicators did not show a difference between online and paper collection, potential implications for others need to be further understood. Key messages • Collecting data through online or paper questionnaires does not lead to major differences in prevalence estimates. • With the rise of online surveys, further assessment is required to understand the potential declaration biases.