The schools and students participating in NAEP assessments are selected to be representative of all schools nationally. The results from the assessed students are combined to provide an accurate estimate of the overall performance of students in public and private schools in the nation.
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 very small schools. Read more technical information about weighting adjustments made at the school and student level.
School and student participation
To ensure unbiased samples, NAEP statistical standards require that participation rates for original school samples be 70 percent or higher to report national results separately for public and private schools. In instances where participation rates meet the 70 percent criteria but fall below 85 percent, a nonresponse bias analysis is conducted to determine if the responding school sample is not representative of the population, thereby introducing the potential for nonresponse bias.
The weighted national school participation rate for the 2012 twelfth-grade economics assessment was 87 percent (88 percent for public schools, 74 percent for private schools, and 86 percent for Catholic schools only). The weighted student participation rate was 85 percent.
A nonresponse bias analysis was conducted for the private school sample. The results of the analysis showed that, while the original responding private school sample may have been somewhat different from the entire sample of eligible schools, including substitute schools and adjusting the sampling weights to account for school nonresponse reduced the potential for nonresponse bias. Although the weighted participation rate for public schools exceeded the 85 percent threshold, a nonresponse bias analysis was conducted for the public school sample because there were no participating public schools in Texas, which makes up approximately 9 percent of the public
schools nationally. The original responding public school sample differed from the entire sample of eligible schools with respect to several variables; for instance, public schools in the south Census region were underrepresented in the responding sample. Including substitute schools in the assessment sample was not effective in reducing potential bias, as no substitute schools in Texas participated. However, adjusting the sampling weights to account for school nonresponse resulted in the reduction of potential nonresponse bias.
Because twelfth-grade participation rates for economics in 2006 fell below 70 percent for private and Catholic school samples, only the 2006 results for public schools are reported separately.
School and student participation rates in NAEP economics at grade 12, by type of school: 2012