Is the school entrance examination a door opener for health sciences research? : Analyzing study participation of hard-to-reach groups

Additional scientific surveys within the compulsory school entrance examination (SEE) have become increasingly popular, partly because the SEE potentially reaches all socioeconomic groups. However, it has not been sufficiently explored whether selective participation in voluntary supplementary surveys actually results in no selection bias along socioeconomic characteristics. Therefore, the aim of this study is to analyze the participation of potentially hard-to-reach families in a parent survey at the SEE. The parent survey on the utilization of community prevention has been linked to the SEE in a community in North Rhine-Westphalia. We compared families with low and higher education (CASMIN classification), families with and without migration background (at least one parent was not born in Germany), as well as single-parent and two-parent families. Using logistic regression we analyzed whether survey participation (n = 3410) and non-participation (n = 346) was different along all three indicators. Families with low education were slightly more often among the group of participants compared to non-participants (11.2 vs. 8.8%; odds ratio (OR) 1.29; 95% confidence interval (CI) 0.85-1.95) and single-parent families slightly less often (14.1 vs. 17.7%; OR 0.75; 95% CI 0.55-1.02). Families with migration background participated significantly more often (52.9 vs. 46.1%; OR 1.27; 95% CI 1.01-1.60). Hard-to-reach families could be recruited for a voluntary parent survey in the SEE to a satisfying degree. This illustrates the potential of the SEE for population-based basic and evaluation research.