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Unformatted text preview: o missing or inconsistent responses. Results for 1978–2004 are from the original assessment format, and results for 2008 and 2012 are from the revised
assessment format (2004 revised assessment format results are not available). Detail may not sum to totals because of rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), various years,
1978–2012 Long-Term Trend Mathematics Assessments. TRENDS IN ACADEMIC PROGRESS 2012 49 T ECHNICAL NOTES Technical Notes
Sampling and Weighting
The target population for the 2012 NAEP long-term trend assessments consisted of 9-, 13-,
and 17-year-old students enrolled in public and private schools nationwide. Eligibility for the
age 9 and age 13 samples was based on the calendar year. Students in the age 9 sample were
9 years old on January 1, 2012, with birth months January 2002 through December 2002.
Students in the age 13 sample were 13 years old on January 1, 2012, with birth months January
1998 through December 1998. Students eligible for the age 17 sample had to be 17 years old on
October 1, 2012, with birth months October 1994 through September 1995.
The national samples for students at ages 9, 13, and 17 were chosen using a multistage design
that involved drawing students from the sampled public and private schools across the country
(table TN-1). Within each age group, the results from the assessed students were combined to
provide accurate estimates of the overall performance of students in the nation.
Table TN-1. Number of participating schools and students in NAEP reading and mathematics assessments,
by student age group: 2012
Age group Mathematics Schools Students Schools Students Age 9 380 8,700 380 8,800 Age 13 380 8,800 380 8,900 Age 17 370 8,800 360 8,500 NOTE: The number of schools is rounded to the nearest ten. The number of students is rounded to the nearest hundred. Because each school that participated in the assessment, and each student assessed, represents
only a portion of the population of interest, disproportionate representation of subgroups in the
selected sample may occur. Results must be weighted to account for any such disproportionate
representation. This includes oversampling of schools with high concentrations of students from
certain racial/ethnic groups and the lower sampling rates of students who attend small schools. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2012 Long-Term
Trend Reading and Mathematics Assessments. 5 0 THE NATION’S REPORT CARD TECHNICAL NOTES School and Student Participation
The weighted national school participation rates for the 2012 long-term trend assessments are presented in
table TN-2. Although not shown in the table, national student participation rates for 9-, 13-, and 17-year-old
students were 95 percent, 93 percent, an...
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