The African-American sample included 105 participants from the GCP condition, and 92 students from the ICP condition. Assignment to condition was made at the school level. Schools were paired on demographic factors and within the pairs one school was randomly assigned to each condition. There were no differences in proportion of gender, χ2 = .31, p = .58 or pre-intervention scores on the screening measure, t(272) = .63, p = .53, between African-American children who were successfully genotyped (n = 197) and those who declined to provide DNA or whose DNA was not usable (n = 77).
