Potential bias in classroom research: comparison of children with permission and those who do not receive permission to participate.

Compared both the social reputation and preference/acceptance of children who received (n = 4,073) and did not receive parental consent (n = 469) to participate in classroom-based sociometric research. Peers and teachers described nonparticipants as less sociable. Peers described nonparticipants as being lower on social acceptance, more aggressive, and less academically competent. No significant differences were obtained for sensitive/isolated characteristics, appearance, or athleticism. There were no significant interactions between consent status and sex or age. Associations between social reputation and social preference scores were similar for participants and nonparticipants. The findings suggest that children who do not return consent forms are systematically different from classmates who participate, although these differences were modest. Further work is needed to determine why children do not participate.