The frame of the private schools in grades 4, 8, and 12 was developed from the 2003-2004 Private School Universe Survey (PSS), a survey conducted by the U.S. Census Bureau for the National Center for Education Statistics (NCES). The PSS is a biennial mail survey of all private schools in the 50 states and the District of Columbia. The PSS frame of schools comprises both a list frame and an area frame. The list frame is an assembly of the 2001-2002 PSS frame and more up-to-date lists from state education agencies, private school associations, and other easily accessible sources. To improve the coverage of the PSS list frame, the Census Bureau also conducted a survey to locate private schools in a random sample of geographic areas throughout the United States. The areas were single counties or groups of counties sampled from an area frame constructed from all counties in the nation. Within each selected area a complete list of private schools was gathered using information from the Yellow Pages, religious institutions, local education agencies, chambers of commerce, and local government offices. Schools not already on the list frame were identified and added to the frame of private schools. A weighting component was computed by the Census Bureau so that the additional area-frame schools would represent all schools absent from the list frame, not just those in the selected area.
|Grade||Affiliation||Schools||Estimated enrollment (unweighted)||Estimated enrollment (weighted)|
|SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2006.|
The sampling frame was restricted to schools located in the primary sampling units (PSUs) selected for NAEP 2006. In addition, the sampling frame excluded all schools that were ungraded, classified as vocational with no enrollment, provided only special education, were home school entities, juvenile correctional institutions, or were parts of prisons or hospitals.
Estimated grade enrollment for private schools is the number of students in the grade as shown on the PSS, if available. If the grade-specific count is not available, the estimated grade enrollment is the average grade enrollment for grades 1 through 8 (for the fourth- or eighth-grade assessments) or the average grade enrollment for grades 9 through 12 (for the twelfth-grade assessment). The following table presents the number of schools and estimated enrollment for the private school frame by grade. The unweighted estimated enrollment is restricted to the selected PSUs. The weighted estimated enrollment incorporates the PSU weight (inverse of the probability of selecting the PSU), and thus is a national estimate of the number of private school students in the grade.
For quality control purposes, school and student counts from the sampling frame were compared to school and student counts from previous frames (2005). No major issues were found.