Characteristics of NYC public schools reporting and not reporting substantial ILI in spring 2009.

aParticipating schools compared to nonparticipating schools.bChi-square test.§Satterthwaite T-test of Mean Difference, two-sided exact Pr>|t|.*A federal program that provides financial assistance to Local Education Agencies and schools with high numbers or high percentages of poor children.†The percentage of public schools where ≥75% of students are eligible for free or reduced price lunch.¶Proportion of each ethnic group in schools.