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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → IRT Parameters for the Mathematics Assessments → IRT Parameters for Items in the Geometry Scale, Grade 8 Mathematics Combined National and State Assessments, By Item and Block: 2011

NAEP Technical DocumentationIRT parameters in the geometry scale, grade 8 mathematics combined national and state assessments, by item and block: 2011
Block Item NAEP ID aj bj cj dj1 dj2 dj3  dj4 
† Not applicable; c parameters are not estimated for generalized partial credit models, and d parameters are not estimated for two-parameter or three-parameter logistic models.
NOTE:  For item j, aj represents the discriminatory power of the item, bj represents a location parameter related to item difficulty, cj represents the guessing parameter, and dji represents the category threshold parameter for category i. The c parameter value is exactly zero for items scaled with the two-parameter logistic model. For item j, dji may not sum to zero because of rounding.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2011 Mathematics Assessment.
MC 3 M150001 1.08 0.80 0.49 † † † †
6 M150301 1.33 0.36 0.11 † † † †
MD 1 M151301 0.92 -0.57 0.12 † † † †
3 M151501 0.75 -0.31 † 0.29 -0.29 † †
ME 3 M221203 0.55 0.98 † 2.31 -2.31 † †
7 M221501 0.72 -1.50 0.20 † † † †
MF 3 M140601 0.68 -1.41 0.19 † † † †
9 M141201 0.81 0.75 0.20 † † † †
11 M141401 0.61 0.75 0.16 † † † †
14 M141701 0.90 1.03 0.12 † † † †
MG 4 M170101 0.17 -0.64 † -5.34 5.34 † †
7 M168201 0.83 0.35 0.16 † † † †
15 M168401 1.05 1.84 0.11 † † † †
MH 2 M167801 0.84 0.11 0.15 † † † †
11 M170501 0.49 -0.41 † -1.07 1.07 † †
13 M164901 0.90 0.88 0.07 † † † †
14 M166901 1.38 1.29 0.36 † † † †
MI 2 M166401 1.43 0.16 0.30 † † † †
7 M166701 0.65 0.07 0.18 † † † †
12 M124901 0.71 0.24 0.27 † † † †
14 M124001 1.02 1.18 0.09 † † † †
MJ 4 M222701 0.54 -0.04 † -3.81 3.81 † †
14 M223701 2.07 1.45 0.17 † † † †
MK 2 M170901 1.00 -0.31 0.19 † † † †
10 M169101 1.08 2.07 0.35 † † † †
16 M171201 0.93 1.11 0.15 † † † †
ML 1 M152701 1.27 -0.41 0.22 † † † †
4 M153001 1.02 -0.49 0.32 † † † †
8 M153401 0.86 1.10 0.19 † † † †
14 M154001 0.75 0.34 0.09 † † † †
Last updated 30 June 2014 (GF)
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