NAEP Technical DocumentationSubstitute Public Schools for the 2012 Long-Term Trend (LTT) Assessment

Substitute schools were preselected for the public school samples by sorting the school frame file according to the actual order used in the sampling process (the implicit stratification). For operational reasons, the original selection order was embedded within the sampled primary sampling unit (PSU) and state. Each sampled school had each of its nearest neighbors within the same sampling stratum on the school frame file identified as a potential substitute. When age-eligible enrollment was used as the last sort ordering variable, the nearest neighbors had age enrollment values very close to that of the sampled school. This was done to facilitate the selection of about the same number of students within the substitute as would have been selected from the original sampled school.

Schools were disqualified as potential substitutes if they were already selected in any of the original public school samples or assigned as a substitute for another public school (earlier in the sort ordering). Schools assigned as substitutes for age 17 schools were disqualified as potential substitutes for age 9 and 13 schools, and schools assigned as substitutes for age 13 schools were disqualified as potential substitutes for age 9 schools.

If both nearest neighbors were still eligible to be substitutes, the one with a closer age-eligible enrollment was chosen. If both nearest neighbors were equally distant from the sampled school in their age enrollment (an uncommon occurrence), one of the two was randomly selected.

Of the approximately 1,100 original sampled public schools for the ages 9, 13, and 17 assessments, about 30 schools had a substitute activated because the original eligible school did not participate. Ultimately, about 20 of the activated substitute public schools participated in an assessment.

Last updated 05 June 2013 (JL)

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