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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. The data in these surveys are reported annually by SEAs.

Participation in 2009–10. The data are collected 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 for the original 1a version of the report were extracted from EDFacts between April 29, 2010, and January 3, 2011. In June 2012, NCES conducted a special collection effort to improve data quality on the 2009–10 LEA universe file. This revised report includes corrections made by states resulting from this special collection effort which were extracted from EDFacts on July 18, 2012. Further updates from states may be included in subsequent file releases.

Totals. "United States" and "reporting states" totals 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. 

Missing data. Not all states collect and report all of the data items requested in the CCD surveys. National Center for Education Statistics (NCES) attempts to correct missing data first by drawing on other sources. For example, a state may be 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. NCES also carries some information, such as address or telephone number, forward from a prior year’s report if it is missing in the current year. For example, American Samoa and Guam last reported data for the 2006–07 CCD files. (Statistical information, such as the number of students in membership, would not be carried forward, if any of the corresponding directory data were submitted by a state.) These procedures are used for any data item, and for all of the three nonfiscal CCD surveys.

While NCES does not impute (replaces a nonresponse with a plausible value) missing items in the Public Elementary/Secondary School Universe Survey or the Local Education Agency Universe Survey (used in this report), NCES imputes some missing items in the State Nonfiscal Survey of Public Elementary/Secondary Education.

When reporting results, NCES treats missing data within individual states differently than it treats missing data across all states and the District of Columbia. An individual state is considered to have missing data if an item is reported for less than 80 percent of possible cases. 

If information is missing for some, but no more than 15 percent, of possible cases across the 50 states and 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 Public Elementary/Secondary School Universe Survey 2009–10 file.

EDFacts collection system accepted blank responses in 2009–10 school year reports and did not require that states distinguish among missing, not applicable, and "zero" values. Various edits were used to correctly identify responses as missing, not applicable, or zero after the fact, but it is possible that some blank responses were categorized incorrectly. For example, blank staff counts may have been categorized as missing when the actual count was 0. Detailed information about the edits is included in the documentation for the Public Elementary/Secondary Local Education Agency Universe Survey 2009–10 file.

Data quality. NCES performed extensive quality review of all CCD data submissions. Data editors 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 is forthcoming for anomalous data, NCES either edited the value (as an example, replace a reported value with the sum of detail) or changed it to missing. For example, if a state’s number of 12th-grade students was substantially larger than the number of students in grade 11 in the previous year, and the state could not explain the discrepancy, NCES would change the reported number of 12th-grade students to missing.

NCES also applied additional data edits to all three data files to reduce data anomalies. For example, in 2009–10, some states reported more full-time equivalent (FTE) counts at the school level than the local education agency (LEA) level and the states confirmed that the LEA figures were accurate. NCES edited the FTE data at the school level to match the data at the LEA level. More information about the edits is included in the documentation for the Public Elementary/Secondary School Universe Survey 2009–10 file, which can be accessed at http://nces.ed.gov/ccd/ccddata.asp

Special collection effort to improve data quality. In May 2012, NCES became aware of data errors for key data items for several schools on the published version of the SY 2009–10 school file; in some cases these errors also affected district level data on the published 1a version of the LEA universe files for SY 2010–11. As a result, NCES conducted an in depth quality review of both the school and LEA universes for both the published SY 2009–10 school and LEA universe files and not yet published SY 2010–11 school and LEA universe files. During this review, NCES developed a revised editing strategy that more accurately identified data items that were likely to have errors. The review focused on school and school district enrollment, grade 12 enrollment, and free and reduced price lunch variables and related ratios such as pupil/teacher ratio, percent of enrollment from grade 12, and percent of students eligible for free and reduced price lunch. In the past data items were only compared to the reported data from the prior year for each school or LEA. The revised methodology used data from multiple years and was applied to both the reported data items and related ratios. Specifically, an average variation over the prior 4 years was computed based on the differences between each year and the other 3 years. Then, the average variation between the target year and the four preceding years was computed based on the differences between target year and each of the 4 prior years. The average variation for the target year was compared to the average variation among the prior years; cases with large differences were flagged as potential errors. Additionally, a requirement was added that in order for an item to be identified as a potential error, both the count and a related ratio must be identified as potential errors. For example, for total student membership to be flagged as a potential error, both total membership and a related ratio, such as pupil/teacher ratio, must be flagged.

NCES subsequently applied this revised editing methodology to both the SY 2009–10 and SY 2010–11 school and LEA universe files. This resulted in identification of over 1,000 questionable data items in the school and LEA universe files for both school years. In June 2012, NCES generated edit reports for each state with affected data items and provided these to the SEA EDFacts coordinators asking them to submit corrected data or provide a justification for the large variation in the reported data. In most cases, SEAs provided corrections of the data items in question or provided an acceptable explanation for the apparent data anomaly. CCD Survey staff reviewed the revised data and explanations submitted by SEAs to ensure that revised data were of acceptable quality and that any unchanged items were adequately explained. For data items that were not adequately resolved CCD Survey Staff applied suppression codes indicating that these items did not meet NCES data quality standards. This report is based on the 2009–10 version provisional 2a data file, which contains revisions to only the data items that NCES identified as potential errors during this process.

School and agency operational and membership status. In order to ensure continuity over time, the CCD includes schools and agencies that may not be operating during the school year reported. "Inactive" schools are those that are closed temporarily, with the intention that they will be reopened; inactive schools retain their original NCES identification code. "Closed" schools are reported for one year after they have been closed. "Future" schools are those that are scheduled to open, but have not yet begun to operate.

Some operational schools or agencies may legitimately not report students. The CCD allows a student to be reported for only a single school or agency. A vocational school or a local education agency (LEA) operating only vocational schools may provide classes for students from a number of regular schools or school districts. In this case, the students are usually reported in the membership of their school of record, and the vocational school (identified as a "shared time" school) shows no student membership. It is also possible that an operational school that is not "shared time" can be reported with no membership. For example, the number of students may be missing, or the school may not have enrolled students at the time it was reported.

Agreement across survey levels. Some students receive a public education outside a regular school district (for example, they may attend a state-operated residential school). Some students in a regular school district may not be served by a school. For example, hospitalized and homebound students may be reported in the membership for a regular school district but not for any of the district’s schools. NCES derived 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.

New York City Public Schools.  In 2003–04, New York began reporting the New York City Public Schools as 33 separate sub-districts that are components of a supervisory union, the New York City Public Schools. This report combines the sub-districts into a single regular school district. 

Bureau of Indian Education Schools. In 2009–10, the Bureau of Indian Education reported each school on both the school file and the agency file. In prior years, the schools were listed only on the school file.

Staff counts. All staff counts (including teachers) are reported in 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.

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