The resurgence of the measles has drawn scrutiny to California’s fairly lenient vaccine policy, which allows parents to choose a personal-belief exemption to avoid vaccinating their kids. And while parents can send their non-inoculated children to school, the state also publishes detailed information on the vaccination rates at every public and private school in the state.
By comparing this information with characteristics of each school, we were able to draw a detailed picture of what sort of schools are attended by children of vaccine-skeptic parents. Here’s a breakdown by a few different school characteristics.
Vaccination rates go down with the percentage of students receiving free or reduced lunch—which is the best school-by-school economic indicator available. In other words: The better off the parents are, the more statistically likely they are to apply for personal-belief exemptions against the otherwise mandatory vaccinations.
Though it’s less commonly discussed, the religious affiliation of a school is also a useful predictor of vaccination rates. (As with all statistical correlations, this does not mean it is the religion that is dictating the choice not to vaccinate.) Baptist and Calvary Chapel schools are particularly likely to have unvaccinated students, though overall, private religious schools have higher vaccination rates than non-religious private schools.
And though they account for only 661 students, Waldorf schools (as identified by the name of the school) have extremely high rates of personal-belief exemptions, to the tune of 38 percent. Mother Jones caught up with a dean at one such Waldorf school who explained that, while there was no recommended policy on vaccines, she was accepting of whatever choice parents made.
The raw data for this story is available for download on TIME’s GitHub account. The vaccination data was matched to public and private school registries as well as data on free and reduced lunch programs by school. The correlation between the percentage of students receiving free or reduced lunch and the rate of personal belief exemptions is -0.29, and the correlation with the number of enrolled students is -0.18.