NAEP Assessment Sample Design → NAEP 2008 Sample Design → Selection of Primary Sampling Units (PSUs) for the 2008 Assessment → Final Primary Sampling Unit (PSU) Sample

NAEP Technical DocumentationFinal Primary Sampling Unit (PSU) Sample

For the Arts assessment, a primary sampling unit (PSU) sample was drawn independently from each of the 76 noncertainty strata defined in Final Primary Sampling Unit Strata. One PSU was selected with probability proportionate to size (with size equal to estimated number of youths) within each stratum.

For the Long-Term Trend (LTT) assessment, fewer PSUs were needed due to the smaller required student sample size. To accomplish this, the 76 noncertainty strata were paired and one stratum from each of the 38 pairs was randomly selected. Methods were employed to reduce the overlap of the 38 LTT noncertainty sample PSUs and those already selected for the arts assessment. Even so, three of the LTT noncertainty PSUs were selected for the arts assessment as well.

Also, 29 PSUs were included in the sample of PSUs with certainty for both the arts and the LTT assessments.

Distribution of sampled primary sampling units (PSU) for arts and long-term trend (LTT) assessments by PSU type: 2008

PSU type	Number of sampled PSUs
	Arts	LTT
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2008 Arts and Long-Term Trend Assessments.
Total	105	67
Metropolitan status
Metropolitan	83	56
Non-metropolitan	22	11
Census Region
Northeast	15	10
Midwest	23	14
South	42	26
West	25	17
Certainty/metropolitan status
Certainty	29	29
Non-certainty metropolitan	54	27
Non-certainty non-metropolitan	22	11

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