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) through the efforts of State CCD Coordinators. Participation in the CCD is voluntary.

The data are collected from SEAs through an online reporting system. They are then processed, edited, and verified by the U.S. Census Bureau, the National Center for Education Statistics (NCES), and the Education Statistics Services Institute (ESSI) of the American Institutes for Research (AIR). The 2005–06 school year CCD collection opened on March 15, 2006 and closed on October 1, 2006.

Data quality.

Staff at NCES, the Census Bureau, and ESSI 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 is forthcoming for anomalous data, NCES will change the value (example, replace a reported value with the sum of detail) or change it to "not available." For example, if the number of high school diploma recipients is substantially larger than the number of students in grade 12 the previous year, and the state cannot explain the discrepancy, NCES would change the reported number of diploma recipients to not available.

Missing data.

Not all states collect and report all of the data items requested in the CCD surveys. 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 correct missing items. When this is done, table footnotes identify all instances in which data were imported from outside sources. This procedure is used for any data item, and for all of the three nonfiscal CCD surveys.

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

An individual state is considered to have missing data if an item is reported by less than 80 percent of its schools or agencies. If a state is missing 20 percent or more of its responses for a given data item in the school or local education agency surveys, the corresponding table cell is suppressed and no count is presented. For example, in table 2, Title I status was suppressed for New Jersey because the Title I school indicator was missing for more than 20 percent of the schools in the state. Precise information about the extent of missing data is included in the documentation for the Public Elementary/Secondary School Universe Survey 2005–06 file, which can be accessed at http://nces.ed.gov/ccd/pubschuniv.asp.

Missing data are treated differently across states and the District of Columbia as a whole than they are within individual states. When data are reported across states, if information is missing for no more than 15 percent of schools across the United States, NCES calculates totals and identifies them as totals for "reporting states," rather than for the United States, and column headings are labeled accordingly. Data that are suppressed because of underreporting are not included in "reporting states" totals. For example, a "reporting states" total was calculated for the total number of magnet schools in table 2. This is because the 13,276 schools in the 8 states for which this information was missing or underreported made up less than 15 percent of all schools in the 50 states and the District of Columbia.

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Totals.

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 Marianas Islands, or the U.S. Virgin Islands. In cases where not all of the 50 states and the District of Columbia provided a response for a data item, but a response was missing for no more than 15 percent of the schools in the 50 states and the District of Columbia, a "reporting states" total is presented. (See "Missing data" for more information.)

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, and they 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 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.

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. Hospital-homebound students, for example, may be reported in the membership for a regular school district but not for 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 Education Survey 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.

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