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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for the Physical Science Scale, by Block and Item, Grade 8 Science National Main Assessment (Accommodations Permitted [R3]): 2000
NAEP Technical DocumentationIRT parameters for the physical science scale, by block and item, grade 8 science national main assessment (accommodations permitted [R3]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3 dj4
S3 1 K040601 0.64 -0.10 0.00
2 K0406CL 0.70 0.89 0.00 -0.00 0.00
3 K040603 0.64 -0.61 0.00
4 K040604 0.79 0.13 0.00
5 K040605 0.47 0.54 0.00 0.43 -0.43
6 K040606 0.90 -0.26 0.00 1.76 -1.76
S6 6 K031309 0.29 -2.71 0.00 -4.65 2.12 2.53
7 K031302 0.47 1.04 0.00
8 K031305 0.71 1.67 0.00
9 K031306 0.58 3.18 0.00
S10 9 K095901 0.58 1.41 0.00 1.23 -1.23
10 K093601 0.77 1.74 0.00 0.56 -0.56
11 K095301 1.14 0.78 0.47
14 K095101 0.75 0.71 0.24
15 K095801 0.61 1.21 0.00
16 K095501 0.98 1.53 0.12
S11 4 K042801 1.04 1.26 0.18
5 K042901 1.70 1.81 0.25
10 K043201 0.36 0.25 0.26
13 K043501 0.62 -0.03 0.00 1.36 -1.36
14 K043601 0.76 -0.04 0.00
15 K043602 0.54 2.92 0.00 -0.54 0.54
16 K043603 0.72 -0.99 0.00
S12 1 K046801 0.46 0.59 0.29
2 K046901 0.96 0.42 0.26
4 K047101 1.24 0.23 0.21
5 K047201 0.53 0.38 0.00 0.23 -1.19 0.95
7 K047401 0.62 0.97 0.00 -0.40 0.40
12 K047901 0.95 0.32 0.00
S13 1 K048201 1.27 0.73 0.19
4 K048501 1.06 1.10 0.32
5 K048601 0.54 1.02 0.00 1.07 -1.07
9 K049001 0.65 3.24 0.00 -1.97 1.97
10 K049101 0.63 -0.28 0.17
S14 1 K035401 0.76 1.55 0.44
3 K035601 0.29 0.76 0.00
4 K035701 0.86 0.64 0.19
5 K035801 0.56 -0.57 0.00 -0.33 0.33
8 K036201 0.85 0.53 0.12
9 K036301 0.50 0.36 0.00 -1.67 1.67
13 K036601 0.53 -0.25 0.18
16 K036901 0.70 -0.36 0.18
S15 4 K037301 0.38 1.06 0.00 -2.24 2.24
6 K037501 0.74 2.09 0.00 -0.24 0.24
8 K037701 0.32 -3.04 0.00 0.29 1.48 -1.77
9 K037703 0.47 0.73 0.00 0.39 -0.39
11 K037901 0.95 2.04 0.22
16 K038301 0.77 1.32 0.00 2.25 0.82 -1.04 -2.03
S20 2 K094001 0.36 1.46 0.23
4 K096001 0.60 0.12 0.26
6 K095601 1.00 -0.07 0.21
7 K095401 0.47 2.79 0.00 0.88 -0.88
11 K096201 0.88 1.63 0.26
14 K095201 0.66 0.68 0.21
15 K093701 0.59 1.13 0.00 0.67 -0.67
16 K097001 0.29 2.80 0.00 0.37 -0.37
S21 3 K045401 1.15 0.40 0.57
4 K045501 0.80 0.90 0.29
7 K045801 0.58 1.29 0.00 1.62 -1.62
8 K045901 0.73 1.09 0.39
11 K046201 0.63 1.82 0.32
14 K046501 0.65 1.23 0.00 0.68 -0.68
15 K046601 0.76 -0.03 0.00
† Not applicable; the number of item parameters estimated depends upon the IRT model used for scaling.
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 is the category threshold parameter for category i. The c-parameter value is exactly zero for items scaled with the two-parameter logistic model or the generalized partial credit model.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000 Science Assessment.

Last updated 15 July 2008 (DR)

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