A Comparison of Methods of Increasing Parental Consent Rates in Social Research

Previous research on children requiring written parental consent has indicated that this requirement reduces samples to half the size they might otherwise be and results in overrepresentation of whites and underrepresentation of blacks. Within the course of a four-year study, four methods were utilized to increase parental consent rates, particularly for black students. All methods increased consent rates. Providing an incentive to the parents increased consent rates significantly more for the white students than for the black students, while communication with the children and incentives to the children resulted in consent rates which were more similar for the two racial groups. Communication with the parents was the most effective method for both black and white children, but was also the most time consuming. Teresa L. Thompson is a Senior Faculty member, American Center for Management Development, Sarasota, Florida. This research was supported in part by Grant No. G007900083 from the Department of Education and by grants from the University of Delaware. The author thanks Lou Cusella and Dan Slater for helpful comments on an earlier draft of this paper. Public Opinion Quarterly Vol. 48:779-787 ? by the Trustees of Columbia University Published by Elsevier Science Publishing Co., Inc. 0033-362X/84/0048-779/$2.50 This content downloaded from 157.55.39.46 on Mon, 13 Jun 2016 06:00:46 UTC All use subject to http://about.jstor.org/terms 780 TERESA L. THOMPSON Two studies have investigated how the need to obtain parental consent, in particular, will bias a sample. In a comparison of a consenting sample to the entire population, no differences were discovered in grade point average or intelligence scores (Lueptow, et al., 1977). More recently, Kearney, et al. (1983) found that, among whites, parents of students with the highest reading and vocabulary scores were most likely to consent. Those who denied permission had children with somewhat lower scores, and those who did not reply had children with the lowest scores. Among Asian students, the highest scores were observed among those whose parents denied permission, followed by those who consented and those who did not reply. The scores of all three groups of black students were virtually identical. When the sample was compared to the population rather than to those who refused consent, no significant differences were discovered on reading or vocabulary scores. One blatant bias in the sample, however, seemed to be in its racial makeup. Whites were overrepresented, while blacks and Asians were underrepresented. Achieving racial composition in the sample consistent with the population is an ever-present concern to researchers. It appears, then, that what needs to be examined are methods for increasing parental consent rates, particularly among underrepresented groups. Most previous research has used a series of two follow-up letters with consent forms to achieve a 50 percent response rate. Hirschi (1968) had only 12 percent of the parents refuse participation or not reply, but he had field workers visit homes to persuade parents. This method is, in most cases, prohibitively expensive. The goal of the present investigation was to examine other methods of increasing response rates, particularly among black students. Procedures for Improving Consent Rates Within the course of a large-scale investigation of the social consequences of the mainstreaming of physically disabled children into "regular" classrooms, parental consent for participation was sought for 1,314 children over the course of four years. Positive responses to the initial request were under 25 percent, so a series of procedures was utilized with different groups of subjects at various times to increase participation. Along with a follow-up letter, the following methods were utilized in different conditions: (1) an incentive to the child for participation; (2) an incentive to the parent; (3) communication with the child about the study; and (4) communication with the parents about the study via a phone call. The overall consent rate and the consent rate for whites vs. blacks were examined. This content downloaded from 157.55.39.46 on Mon, 13 Jun 2016 06:00:46 UTC All use subject to http://about.jstor.org/terms INCREASING PARENTAL CONSENT RATES 781