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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.

Participation in 2009–10. The data are collected annually from SEAs through the Department of Education’s EDFacts collection system. The 50 states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, and the Bureau of Indian Education participated in EDFacts for the 2009–10 school year; the Department of Defense dependents schools (overseas and domestic) and the Commonwealth of the Northern Mariana Islands reported directly to the CCD. American Samoa and Guam did not report data for the 2009–10 school year.

States report data to the EDFacts collection system through multiple file groups that fall into different reporting schedules throughout the year. The 2009–10 school year EDFacts collection of CCD data opened in January 2010. Depending on the specific variable or state, the data were extracted from EDFacts between April 29, 2010 and January 3, 2011. Late reports or updates from states may be included in subsequent file releases.

Data quality. The National Center for Education Statistics (NCES) performs extensive quality review of all CCD data submissions and asks state CCD coordinators to correct or confirm any numbers that appear out of range when compared to other states’ data or with the state’s reports in previous years. If no explanation for anomalous data is provided by the state, NCES edits 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 also edits values 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 or jurisdictions collect and report all of the data items requested in CCD surveys. NCES attempts to complete missing data first by drawing on other sources. For example, if the number of teachers was missing in the State Nonfiscal Survey of Public Elementary/Secondary Education, but reported in the Local Education Agency Universe 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 complete 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 complete missing data are used for any CCD data item and for all three CCD nonfiscal surveys.

If NCES cannot complete missing data 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 of Public Elementary/Secondary Education. (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 edited data. NCES imputes and edits 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 edits are performed on data from the 50 states and District of Columbia only.

  • Imputations provide plausible values in cases where the data are missing. An imputation assigns a value to the missing item; as a result, subtotals containing this item increase by the amount of the imputation. An example of one of the imputation methods used is the following: 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. For more information about the imputation procedures used to assign values to missing items, please refer to the documentation for the State Nonfiscal Survey of Public Elementary/Secondary Education.
  • Edits are corrections for reported values. There are several variations in the way edits are carried out. An example of one of the edits is the following: if a state reports a total count of teachers that exceeds or is less than the sum of associated detail counts, but none of the associated components has been imputed, the reported total is edited to equal the sum of the associated detail counts. For more information about the procedures used to edit reported data, please refer to the documentation for the State Nonfiscal Survey of Public Elementary/Secondary Education.

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.

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. For example, hospital-bound or homebound students may be reported in the membership for a regular school district but not in any of the district’s schools. NCES derives the numbers of students and staff shown in the tables for any CCD First Look report 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 Education are 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 (including teachers) into one. In these cases, for the state nonfiscal data only, NCES edits 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 edited.

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