Education's Report Card

For example of the 157 questions that made up the

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Unformatted text preview: 7. Three percent of the mathematics assessment at age 13 was also administered to both 9and 17-year-old students. Figure TN-2. Percentage distribution of NAEP mathematics assessment questions administered at and across   student age groups: 2012 Age group NOTE: Detail may not sum to totals because of rounding. The 1973 Mathematics Results The mathematics trend scale was developed in 1986 for all the assessment years up to that point. Because the 1973 mathematics assessment had too few questions in common with the 1978, 1982, and 1986 assessments, results from the 1973 assessment were placed on the same 0 to 500 mathematics scale using mean proportion correct extrapolation. Estimates were extrapolated from the data so that average mathematics scores could be reported for the nation and by race/ethnicity and gender at all three ages. The extrapolated estimates for each age level were obtained by assuming a linear relationship between a student group’s average scale score and the logit transformation of the group’s average percentage of correct responses. The same linear relationship was assumed to hold across assessment years and student groups within an age level. For more information, see the Mathematics Data Analysis chapter in Expanding the New Design: The NAEP 1985-86 Technical Report. Because of the need to extrapolate the average scale scores, caution should be used in interpreting the pattern of trends across those assessment years. 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 Mathematics Assessment. 52 THE NATION’S REPORT CARD TECHNICAL NOTES Interpreting Statistical Significance NAEP reports results using widely accepted statistical standards. Significance tests in the form of t-tests are conducted to determine if estimates are significantly different from each other. Findings are reported based on a statistical significance level set at .05 with appropriate adjustments for multiple comparisons. Comparisons over time or between groups are based on statistical tests that consider both the size of the differences and the standard errors of the two statistics being compared. Standard errors are margins of error, and estimates based on smaller groups are likely to have larger margins of error. The size of the standard errors may also be influenced by other factors, such as how representative the assessed students are of the entire population. When an estimate has a large standard error, a numerical difference that seems large may not be statistically significant. Differences of the same magnitude may or may not be statistically significant depending upon the size of the standard errors of the estimates. Standard errors for the estimates presented in this report are available at http:/ /nces.ed.gov/nationsreportcard/lttdata/. When making multiple simultaneous comparisons, error rates are controlled to ensure that significant differences in NAEP data reflect actual...
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This document was uploaded on 02/28/2014.

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