NAEP Technical DocumentationStudent Sample Selection for the 2005 National Private School Assessment

The general target for all three grades for the student sample size per sampled school was 120. If the school had up to 136 grade-eligible students, then all were taken into the sample. If the school had more than 136 grade-eligible students, then a sample of 120 students was drawn using equal probability systematic sampling.

Students were assigned to four sessions for fourth- and eighth-grade reading and mathematics operational assessments, science bridge, science operational, and pilot. For twelfth grade, there were only three sessions with reading, mathematics, and science operational collapsed together. Session assignment probabilities varied by school type and grade according to the assessment targets and are shown in the table below.

NAEP private school study probabilities for assessment assignments, by school type and grade: 2005
Grade	Sessions	Target percent Catholic schools	Target percent Lutheran schools	Target percent Conservative Christian and other private schools
4	Operational reading and mathematics	73.85	87.66	71.30
	Science bridge	7.69	3.57	8.33
	Operational science	15.55	1.39	17.15
	Pilot	2.91	7.38	3.22
8	Operational reading and mathematics	73.85	87.66	71.30
	Science bridge	7.69	3.57	8.33
	Operational science	15.28	7.26	18.86
	Pilot	3.18	1.51	3.51
12	Operational reading, mathematics and science	78.75	78.75	78.75
	Science bridge	12.50	12.50	12.50
	Pilot	8.75	8.75	8.75
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005.

Small numbers of students split between science bridge and non-science bridge would have resulted in awkward operational situations (e.g., the requirement of separate classrooms for limited numbers of students). For that reason, in schools with a small number of grade-eligible students, it was preferred that either there be no science bridge assessments, a science bridge sample size that was greater than or equal to 12 (if there were that many students), or science bridge only; (if there were fewer than 12 students).

Schools were classified into five categories based on enrollment. Students were assigned to sessions based on the desired probabilities and the size of the school, taking care to account for the operational issues related to small schools and the science bridge assessment.

The process of list submission, sampling students from year-round schools, sampling new enrollees, and determining student eligibility and exclusion status was the same as for the State NAEP student sample.

Last updated 30 July 2009 (EH)

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