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Public Elementary and Secondary School Student Enrollment and Staff Counts From the Common Core of Data: School Year 2007-08
NCES 2010-309
November 2009

Appendix A: Methodology and Technical Notes

Common Core of Data survey system. The State Nonfiscal Survey of Public Elementary/Secondary Education, the Local Education Agency Universe Survey, and the Public Elementary/Secondary School Universe Survey are the nonfiscal components of the Common Core of Data (CCD) survey system. These surveys are reported annually by state education agencies (SEAs).

Participation in 2007-08. CCD nonfiscal data are collected from SEAs through the U.S. Department of Education's EDFacts system. The 50 states and the District of Columbia participated in EDFacts for the 2007-08 school year; the Department of Defense dependents schools (overseas and domestic), Puerto Rico, and the other jurisdictions of the Commonwealth of the Northern Marianas Islands and the U.S. Virgin Islands reported directly to the CCD. The Bureau of Indian Education, American Samoa, and Guam did not report data for the 2007-08 school year.

The 2007-08 EDFacts collection of CCD data opened in January 2008 and closed in July 2009.

Data quality. Staff at National Center for Education Statistics (NCES), the U.S. Census Bureau, and the Education Statistics Services Institute (ESSI) of the American Institutes for Research (AIR) collaborate to edit all CCD data submissions and ask state CCD coordinators to correct or confirm any numbers that appear out of range when compared with other states' data or with the state's reports in previous years. If no explanation for anomalous data is provided by the state, NCES will change the data value. For example, NCES will replace a reported total with the sum of detail in cases where the sum of detail exceeds a reported total. NCES will also change a value to "not available" if data values are not plausible (e.g., if the number of students increases tenfold from the prior year to the current year while the number of teachers remains unchanged from the prior year, NCES would set the current year value for teachers to not available).

Missing data. Not all states collect and report all of the data items requested in CCD surveys. NCES attempts to correct missing data first by drawing on other sources. For example, if the number of teachers was missing in the State Nonfiscal Survey, but reported in the Local Education Agency Survey, the state-level number would be summed from the state's local education agencies. In some cases, a state is unable to report data during the collection period, but publishes them later, through a written report or website. NCES imports data from these other published sources to correct missing items. When this is done, table footnotes identify all instances in which data were summed or imported from other CCD surveys or outside sources. These procedures to correct for missing data are used for any CCD data item and for all three CCD nonfiscal surveys.

If missing data cannot be corrected by summing from other CCD surveys or using alternate external sources, NCES imputes some missing items (i.e., replaces a nonresponse with a plausible value) in the State Nonfiscal Survey. (See below for information on imputation procedures.) Data are not imputed in the Public Elementary/Secondary School Universe Survey or the Local Education Agency Universe Survey.

If information is missing for some but no more than 15 percent of states across the 50 states and the District of Columbia, NCES calculates totals and identifies them as "reporting states" totals (rather than totals for the United States). Precise information about the extent of missing data is included in the documentation for the State Nonfiscal Survey of Public Elementary/Secondary Education.

Imputed and adjusted data. NCES imputes and adjusts some reported values in the State Nonfiscal Survey of Public Elementary/Secondary Education to create data files that more accurately reflect student and staff counts and to improve comparability among states. Imputations and adjustments are performed on data from the 50 states and District of Columbia only.

  • Imputations provide plausible values in cases in which the missing value is not reported, indicating that subtotals for the category are underreported. An imputation assigns a value to the missing item, and subtotals containing this item increase by the amount of the imputation. For example, if a state is unable to report the number of prekindergarten teachers employed by the state, the number of prekindergarten teachers would be imputed by calculating a median growth rate for all states that reported prekindergarten teachers in the previous and current year, and applying this median growth rate to the previous year's number of prekindergarten teachers.
  • Adjustments are corrections in cases in which a value reported for one item contains a value for one or more additional items not reported elsewhere. For example, a state may not differentiate between kindergarten teachers and prekindergarten teachers, reporting "missing" for prekindergarten teachers and a value representing the count of staff for both categories as kindergarten teachers. NCES adjusts these two responses by reducing the amount reported for kindergarten teachers and adding that amount to prekindergarten teachers.

Totals. United States totals reported in the tables are limited to the 50 states and the District of Columbia. They do not include data from the Bureau of Indian Education, Department of Defense dependents schools (overseas and domestic), Puerto Rico, or the other jurisdictions of American Samoa, Guam, the Commonwealth of the Northern Mariana Islands, or the U.S. Virgin Islands. See "Missing data" (above) for more information.

Agreement across survey levels. Some students receive a public education outside a local school district (e.g., they may attend a state-operated residential school). Some students in a regular school district may not be served by a school. Hospital-bound or homebound students, for example, may be reported in the membership for a regular school district but not in any of the district's schools. The numbers of students and staff shown in the tables for any CCD First Look report are derived from the survey represented in that report. Therefore, the numbers may differ across reports. The numbers reported in the State Nonfiscal Survey of Public Elementary/Secondary Educationare considered the official statistics for a state.

Staff counts. All staff counts (including teachers) are reported in full-time-equivalent (FTE) units. This is the amount of time required to perform an assignment stated as a proportion of a full-time position. It is computed by dividing the amount of time an individual is employed by the time normally required for a full-time position.

State agencies vary in their staff data collection and reporting systems, with resulting variations across states. Several states collapse two or more categories of staff into one. In these cases, for the state nonfiscal data only, NCES adjusts this number by distributing the reported number of staff across the several categories based on the average distribution of these staff in the reporting states. Staff counts in the local education agency and school surveys are not adjusted.