NAEP Technical DocumentationAge Distribution Fractions for Age 17 for the 2012 Long-Term Trend (LTT) Assessment

The derivation of the age distribution factors was much more straightforward than for the age 9 and 13 components. Estimates from the October 2009 Current Population Survey (CPS) School Supplement were utilized to provide the percentages of seventeen-year-olds within each of ninth, tenth, eleventh, and twelfth grades by Census region.

Since the age definition for Age 17 LTT covers students who are born between October of one year and September the following year, with the assessment taking place in about April, in October of the same academic year (i.e. the preceding calendar year), the eligible students are all 16 years of age. Thus the distribution of eligible students in each grade was obtained by considering the proportion of students in each grade who were age 16 from the October 2009 CPS School Supplement. Note that by the time of the LTT assessment, between March and April, the majority of these students are 17 years old. Thus not all students assessed in the Age 17 LTT assessment are aged 17 years, but for simplicity the cohort is referred to as being Age 17. In fact on September 30 of the same academic year as the assessment is conducted, all of the eligible students are aged 16 years.

Last updated 15 July 2013 (PS)

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