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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → IRT Parameters for the Reading Assessments → IRT Parameters for the Reading Vocabulary Scale, Grade 8 Reading Vocabulary National Assessment: 2009
NAEP Technical DocumentationIRT parameters for the meaning vocabulary scale, grade 8 reading vocabulary national assessment: 2009
Block1 Item NAEP ID aj bj cj dj1 dj2 dj3  dj4  dj5 
1 The table includes Meaning Vocabulary items from both the half-blocks as well as the reading vocabulary items embedded within the 25-minute reading comprehension blocks.
† 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), 2009 Reading Vocabulary Assessment.
R1 2 R059602 0.81 -0.02 0.21
8 R059608 0.98 -0.22 0.20
R2 2 R059802 0.37 2.61 0.19
4 R059804 0.99 -0.67 0.25
R3 2 R060102 0.92 -0.25 0.22
9 R060109 1.25 0.46 0.18
R4 2 R060302 1.30 -0.30 0.27
8 R060308 1.03 0.55 0.23
R5 2 R058502 1.27 -0.48 0.23
3 R058503 1.99 -0.44 0.26
R6 5 R058605 1.42 -0.49 0.15
10 R058610 1.37 -0.96 0.16
R7 2 R058802 1.70 -1.15 0.26
8 R058808 1.94 -0.33 0.23
R8 2 R059102 1.28 -1.39 0.11
4 R059104 1.84 -1.41 0.15
R9 9 R060510 0.82 -1.21 0.26
10 R060511 1.56 -0.54 0.28
R11 5 R060806 1.47 -0.64 0.26
8 R060802 0.50 0.35 0.24
R12 7 R061107 1.97 -0.17 0.26
8 R061108 1.57 -0.02 0.22
R13 5 R061305 1.10 -1.13 0.23
6 R061306 1.63 -0.37 0.19
R14 1 R0V0401 2.80 0.76 0.29
2 R0V0402 1.11 -0.77 0.17
3 R0V0403 0.74 0.12 0.18
4 R0V0404 0.65 0.76 0.26
5 R0V0405 0.99 0.64 0.23
6 R0V0406 1.15 0.82 0.31
R15 1 R0V0506 1.22 -0.07 0.14
2 R0V0507 1.67 0.52 0.28
3 R0V0508 0.94 -0.61 0.14
4 R0V0509 0.64 -0.16 0.25
5 R0V0510 1.93 0.51 0.21
R16 1 R0V0206 1.65 -1.23 0.19
2 R0V0207 2.28 -1.15 0.18
3 R0V0208 1.93 -1.28 0.18
4 R0V0209 1.96 -0.74 0.26
5 R0V0210 2.32 -0.95 0.25
R17 1 R0V0306 4.08 -0.45 0.29
2 R0V0307 2.38 -0.77 0.15
3 R0V0308 0.43 -0.10 0.21
4 R0V0309 1.84 -0.77 0.18
5 R0V0310 1.63 -0.24 0.21
R18 1 R0V0601 3.47 -0.10 0.21
2 R0V0602 2.10 -0.60 0.27
3 R0V0603 0.89 -0.23 0.25
4 R0V0604 2.85 -0.45 0.21
5 R0V0605 1.87 -0.47 0.27
R19 1 R0V0708 1.41 -0.37 0.34
2 R0V0709 1.04 -1.06 0.22
3 R0V0710 1.96 0.28 0.29
4 R0V0711 1.30 0.01 0.27
5 R0V0713 2.39 -1.25 0.23

Last updated 03 June 2016 (GF)