For example, parents of less healthy children may be more likely to obtain child health insurance than those of healthier children (adverse self-selection) but may also differ in their demand for prevention. The study sample only includes children without major health issues as described above given that the parent study providing the data for this paper excluded children with major health issues. However, I do adjust for the observed variation in health between the sample children as discussed below. In sum, the health characteristics of the study sample, within-study clinic comparisons and adjustment for several observable confounders are expected to significantly reduce the bias from self-selection into insurance.