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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 Life Science Scale, by Block and Item, Grade 4 Science National Main Assessment (Accommodations Permitted [R3]): 2000
NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 4 science national main assessment (accommodations permitted [R3]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3
S3 2 K0310CL 0.14 1.04 0.00 -17.52 11.33 0.29
3 K031003 0.46 2.85 0.00 1.81 -1.81 †
4 K031004 0.58 -0.43 0.00 † † †
5 K031005 0.43 1.89 0.00 0.89 -0.89 †
6 K031006 0.56 0.04 0.00 0.40 -0.40 †
7 K031007 0.43 0.78 0.00 0.00 -0.00 †
S8 1 K104201 0.52 -2.23 0.16 † † †
2 K103301 0.72 2.65 0.20 † † †
3 K103401 1.42 0.08 0.20 † † †
4 K103601 1.41 0.03 0.21 † † †
5 K103701 0.90 0.49 0.19 † † †
6 K104001 1.18 -0.64 0.28 † † †
8 K104301 1.24 0.64 0.32 † † †
9 K103801 1.02 0.78 0.28 † † †
10 K103901 0.37 1.87 0.00 † † †
11 K104101 1.23 1.02 0.27 † † †
12 K103001 0.84 1.13 0.14 † † †
13 K103101 0.74 3.38 0.00 † † †
14 K103201 0.15 4.79 0.24 † † †
15 K102801 1.19 1.19 0.26 † † †
16 K102901 1.34 1.03 0.28 † † †
S9 1 K031601 0.96 -0.08 0.28 † † †
2 K031602 0.58 0.99 0.00 0.29 -0.29 †
3 K031603 0.66 -0.54 0.00 † † †
4 K031604 0.35 3.88 0.00 1.87 -1.87 †
6 K031606 0.40 2.65 0.00 1.82 -1.82 †
7 K031607 0.94 0.21 0.00 † † †
8 K031608 0.56 3.04 0.00 2.27 -2.27 †
9 K031609 0.61 2.09 0.00 -0.32 0.32 †
S10 1 K031701 0.69 -0.11 0.24 † † †
9 K0325CL 0.43 -0.24 0.00 -0.33 -1.46 1.80
10 K032601 0.86 1.26 0.00 0.85 -0.85 †
11 K032602 0.77 1.37 0.00 † † †
S11 1 K099201 0.51 -1.66 0.31 † † †
5 K098001 0.80 -0.78 0.28 † † †
11 K092201 0.77 1.21 0.00 0.30 -0.30 †
S12 4 K033901 0.80 0.66 0.29 † † †
S13 1 K034601 0.37 0.22 0.25 † † †
2 K034701 0.86 1.82 0.30 † † †
S14 2 K035501 0.40 -0.69 0.27 † † †
6 K035901 0.65 2.14 0.00 † † †
S15 1 K037001 0.91 1.29 0.20 † † †
2 K037101 0.45 -0.89 0.18 † † †
3 K037201 1.04 0.92 0.27 † † †
S20 1 K099101 0.44 -1.25 0.31 † † †
4 K090101 0.47 -1.69 0.22 † † †
7 K098101 0.70 0.37 0.14 † † †
S21 5 K039901 0.43 -0.99 0.00 3.02 -0.92 -1.33
8 K040201 1.28 1.65 0.14 † † †
† 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 14 July 2008 (DR)

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