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NAEP Technical DocumentationSelection of Primary Sampling Units (PSUs) for the 2022 Assessment
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PSU Generation: Metropolitan Statistical Areas PSU Generation: Certainty PSUs |
The first stage of sampling for the 2022 assessment was the selection of
primary sampling units (PSUs). A PSU is a geographic area comprising an individual county or a group of contiguous counties. One set of 105 PSUs was selected for the 2020
long-term trend (LTT) assessments.
The same set of PSUs used for the 2020 assessments was used for the 2022 LTT assessments.
The PSU samples were drawn using a stratified sample design with one PSU selected per stratum or stratum pair with probability proportional to population size. The size measure used for PSU sampling was persons 17 years of age and younger from 2017 U.S. Census Bureau population estimates.
The PSU sampling frame was constructed by partitioning all counties in the entire United States (the 50 states and the District of Columbia) into 1,001 non-overlapping PSUs as follows:
Each metropolitan statistical area (metro area) was considered a separate PSU, unless it crossed census region boundaries. When this happened, the part within each region was made a separate PSU; and
Non-metro area PSUs were constructed from contiguous non-metro area counties within the same state that had minimum populations of 15,000 youths in the Northeast and South census regions and 10,000 youths in the Midwest and West census regions.
Measures of size for constructing the PSUs were based on youth population data obtained from the 2010 Decennial Census summary files.
For the LTT PSU sample, 29 PSUs on the PSU sampling frame were included in the sample with certainty (selected with a probability of 1). The certainty PSUs constitute the 29 largest metropolitan areas in the United States, and for any national sample to be fully representative it is important to include some schools from each of them.
The remaining PSUs were grouped into noncertainty PSU sampling strata within eight primary strata, which were defined by census region and metropolitan status. The stratification of PSUs within the eight primary strata was based on characteristics shown to be highly correlated with student performance such as race/ethnicity composition, income, education, renter status, and percentage of female-headed households. These data were obtained at the county level from the 2006–2010 American Community Survey (ACS) and then aggregated to the PSU level. Seventy-six noncertainty PSU strata were formed. These PSU strata were then paired to form 38 stratum pairs.
Last updated 18 July 2024 (SK)