Parental Informed Consent and Sample Bias in Grade-School Children

The possibility of sample bias resulting from lack of parental consent was investigated in a group of 308 grade-school children for whom sociometric and teacher ratings were available prior to requesting parental consent for a large research project. Children without consent had significantly lower academic performance than those with consent; they were also less popular with peers, who rated them as more withdrawn and aggressive and as less physically attractive. Socially rejected and neglected children were also less likely to obtain parental consent than were socially accepted children. Social withdrawal and poor academic performance were the best independent predictors of nonconsent, accounting for 10% of the variance. However, teacher ratings of various psychological characteristics failed to differentiate children with consent from those without. Findings are discussed in terms of potential bias in child subject samples.