The demographics of the subject population are reported, which is useful in determining the applicability of the results. Patients were recruited from the University of Iowa's faculty general pediatric clinics. Enrollment criteria in this study included parents or guardians willing to enroll, residing with the child, English speaking, having a telephone, and available 2 to 3 weeks later. The study population spoke English only and was largely homogeneous with respect to sex, race, educational level, insurance status, and income. Given this homogeneity, it is unclear to what extent the results are generalizable to other patient populations. Furthermore, as the authors acknowledge, the patient population was higher than the national average on socioeconomic and educational variables.