- Percentage of students approved to receive free or reduced-price lunches through the National School Lunch Program. Private schools that did not participate in the National School Lunch Program were coded as zero. Public schools where the principal stated that no students were eligible or that he/she didn't know if any were eligible were coded as zero. Missing data were imputed conditioning on sector (private, public charter, public non-charter); urbanicity; percentage of students who were part of a minority group; school size; school level; and a composite measure of teachers' perception of the student family background for the population of students in school (based on responses from all teachers sampled as part of SASS, not just beginning teachers.
- The U.S. Census Bureau, (1999), "Schools and Staffing Survey".