- Graduation rate
- The graduation rate is the number of 2004–05 graduates divided by the number of 12th grade students enrolled around October 1, 2004.
- Kindergarten-terminal school
- A school is kindergarten-terminal (k-terminal) if kindergarten is the highest grade offered at the school.
- Private school
- A private school is a school that is not supported primarily by public funds. It must provide instruction for one or more of grades K–12 (or comparable ungraded levels), and have one or more teachers. Organizations or institutions that provide support for home schooling but do not offer classroom instruction for students are not included.
- Program emphasis
- Private schools are classified by respondents in item 12a according to one of seven types of program emphasis:
- Regular: The PSS questionnaire does not provide a definition of this term. Regular schools do not specialize in special, vocational/technical, or alternative education; or in having a Montessori or special program emphasis, although they may offer these programs in addition to the regular curriculum.
- Montessori: The PSS questionnaire does not provide a definition of this term. Montessori schools provide instruction using Montessori teaching methods.
- Special program emphasis: A science/mathematics school, a performing arts high school, a foreign language immersion school, and a talented/gifted school are examples of schools that offer a special program emphasis.
- Special education: Special education schools primarily serve students with disabilities.
- Vocational: Vocational schools primarily serve students who are being trained for occupations.
- Alternative: Alternative schools provide nontraditional education. They fall outside the categories of regular, special education, and vocational education.
- Early childhood: Early childhood program schools serve students in prekindergarten, kindergarten, transitional (or readiness) kindergarten, and/or transitional first (or prefirst) grade.
- Private schools are assigned to one of four geographic regions:
- Northeast: Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Pennsylvania;
- Midwest: Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri, North Dakota, South Dakota, Nebraska, and Kansas;
- South: Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida, Kentucky, Tennessee, Alabama, Mississippi, Arkansas, Louisiana, Oklahoma, and Texas; and
- West: Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, California, Alaska, and Hawaii.
- School level
- Private schools are classified using respondent-provided highest and lowest grades in the school in item 5 according to one of three instructional levels:
- Elementary: A school is elementary if it has one or more of grades K–6 and does not have any grade higher than grade 8; for example, schools with grades K–6, 1–3, or 6–8 are classified as elementary schools.
- Secondary: A school is secondary if it has one or more of grades 7–12 and does not have any grade lower than grade 7; for example, schools with grades 9–12, 7–8, 10–12, or 7–9 are classified as secondary schools.
- Combined: A school is classified as combined if it has one or more of grades K–6 and one or more of grades 9–12; for example, schools with grades K–12, 6–12, 6–9, or 1–12 are classified as having combined grades. Schools in which all students are ungraded (i.e., not classified by standard grade levels) are also classified as combined.
- Any full-time or part-time school staff member who teaches one or more regularly scheduled classes in any of grades K–12 (or comparable ungraded levels).
- Private schools are assigned to one of three major categories (Catholic, other religious, or nonsectarian) and, within each major category, one of three subcategories based on the school's religious affiliation provided by respondents in item 14.
- Catholic: Catholic schools are categorized according to governance, provided by Catholic school respondents in item 14c, into parochial, diocesan, and private schools.
- Other religious: Other religious schools have a religious orientation or purpose, but are not Roman Catholic. Other religious schools are categorized according to religious association membership, provided by respondents in item 14, into conservative Christian, affiliated, and unaffiliated schools. Conservative Christian schools are those "Other Religious" schools with membership in at least one of four associations: Accelerated Christian Education, American Association of Christian Schools, Association of Christian Schools International, or Oral Roberts University Education Fellowship. Affiliated schools are those "Other Religious" schools not classified as Conservative Christian with membership in at least 1 of 11 associations—Association of Christian Teachers and Schools, Christian Schools International, Evangelical Lutheran Education Association, Friends Council on Education, General Conference of the Seventh-Day Adventist Church, Islamic School League of America, National Association of Episcopal Schools, National Christian School Association, National Society for Hebrew Day Schools, Solomon Schechter Day Schools, Southern Baptist Association of Christian Schools—or indicating membership in "other religious school associations." Unaffiliated schools are those "Other Religious" schools that have a religious orientation or purpose, but are not classified as Conservative Christian or affiliated.
- Nonsectarian: Nonsectarian schools do not have a religious orientation or purpose and are categorized according to program emphasis, provided by respondents in item 12a, into regular, special emphasis, and special education schools. Regular schools are those that have a regular elementary/secondary or early childhood program emphasis. Special emphasis schools are those that have a Montessori, vocation/technical, alternative, or special program emphasis. Special education schools are those that have a special education program emphasis.
- Ungraded students
- Ungraded students are those who are not assigned to a particular grade level (kindergarten, first grade, second grade, etc.) For example, special education centers and alternative schools often classify their students as ungraded. Students in Montessori schools are also considered ungraded if the school assigns them to "primary" and "intermediate" levels instead of specific grades.
- Urbanicity type
- Urbanicity type is derived from the twelve-category, urban-centric locale code (ULOCALE). The urban-centric locale code is based on the school's physical address (or mailing address if the physical address is not reported) and is a measure of a school's location relative to populous areas. For this report, the urban-centric locale codes were aggregated into four urbanicity types:
- City: The territory inside an urbanized area and inside a principal city. (ULOCALE = 11, 12, or 13);
- Suburb: The territory outside a principal city and inside an urbanized area. (ULOCALE = 21, 22, or 23);
- Town: Territory inside an urban cluster. (ULOCALE = 31, 32, or 33); and
- Rural: Census defined rural territory. (ULOCALE = 41, 42, or 43).