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HomeTDWNAEP Analysis and ScalingEstimation of NAEP Score ScalesNAEP Assessment IRT ParametersScience Assessment IRT ParametersIRT Parameters for the Physical Science Scale, by Block and Item, Grade 12 Science National Main Assessment (Accommodations Permitted [R3]): 2000
NAEP Technical DocumentationIRT parameters for the physical science scale, by block and item, grade 12 science national main assessment (accommodations permitted [R3]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3
S3 2 K049501 0.30 -2.76 0.00 -3.24 -2.90 6.14
4 K049502 0.31 2.77 0.00 -0.72 0.81 -0.09
5 K049503 0.86 -0.09 0.00 † † †
S6 1 K049701 0.41 -0.39 0.00 -1.04 1.04 †
2 K049702 1.01 -1.16 0.00 † † †
3 K049708 1.21 -0.02 0.00 † † †
4 K049703 1.12 1.58 0.00 † † †
5 K049704 1.17 -0.73 0.00 0.81 -0.81 †
6 K049705 0.74 -0.10 0.00 -0.73 0.73 †
7 K049706 1.37 0.16 0.00 † † †
8 K049707 1.05 1.03 0.00 1.02 -1.02 †
S7 1 K105101 0.65 -0.49 0.34 † † †
2 K105701 1.68 1.27 0.31 † † †
5 K105301 2.54 1.39 0.20 † † †
6 K105901 1.07 0.19 0.33 † † †
7 K106001 0.90 3.93 0.09 † † †
9 K105501 1.17 2.00 0.00 0.23 -0.23 †
S9 12 K049914 0.76 0.68 0.00 -1.23 1.23 †
13 K049912 0.95 1.02 0.00 0.80 -0.80 †
14 K049913 1.19 0.76 0.11 † † †
S10 3 K095701 0.24 1.66 0.28 † † †
8 K096301 0.38 0.66 0.24 † † †
9 K096701 0.67 0.64 0.18 † † †
10 K093301 0.25 1.72 0.29 † † †
11 K098601 0.62 2.07 0.00 0.99 -0.99 †
13 K093101 1.92 1.20 0.49 † † †
15 K096801 0.83 2.86 0.29 † † †
S11 2 K051401 1.26 0.76 0.42 † † †
3 K051501 1.28 1.34 0.33 † † †
7 K051901 1.42 1.87 0.33 † † †
11 K052301 0.38 0.22 0.00 † † †
12 K052401 0.59 1.12 0.00 -0.03 -0.21 0.24
13 K052402 0.50 3.17 0.00 2.69 -2.69 †
S12 1 K046801 0.84 0.12 0.40 † † †
2 K046901 0.74 -0.49 0.17 † † †
4 K047101 1.09 -0.55 0.19 † † †
5 K047201 0.49 -0.45 0.00 0.60 -1.50 0.90
7 K047401 0.48 0.43 0.00 -0.75 0.75 †
12 K047901 1.11 -0.49 0.00 † † †
S13 1 K048201 1.50 -0.18 0.20 † † †
4 K048501 1.00 0.35 0.30 † † †
5 K048601 0.52 0.23 0.00 0.99 -0.99 †
9 K049001 1.35 2.00 0.00 † † †
10 K049101 0.27 -1.06 0.25 † † †
S14 1 K052601 0.65 0.02 0.25 † † †
2 K052701 1.01 0.94 0.20 † † †
7 K053101 0.89 1.62 0.00 † † †
8 K053102 0.61 2.67 0.00 † † †
9 K053201 1.51 1.13 0.11 † † †
10 K053301 2.98 0.73 0.20 † † †
11 K053401 0.48 0.33 0.21 † † †
S20 1 K096601 0.69 -1.49 0.28 † † †
3 K102601 1.00 0.89 0.21 † † †
4 K102701 0.19 -2.73 0.28 † † †
7 K093401 1.17 0.55 0.23 † † †
14 K093201 0.98 0.46 0.26 † † †
15 K096501 1.16 1.94 0.00 -0.01 0.01 †
19 K096401 2.39 1.63 0.09 † † †
S21 1 K058601 0.72 -0.35 0.30 † † †
5 K059001 0.34 -4.44 0.00 † † †
6 K059101 0.50 1.10 0.00 † † †
10 K059501 2.53 1.91 0.08 † † †
† 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 (KL)

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