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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 Not Permitted [R2]): 2000
NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 4 national main science assessment (accommodations not permitted [R2]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3 dj4
S3 2 K0310CL 0.15 0.87 0.00 -14.56 9.77 -0.99 5.78
3 K031003 0.55 2.54 0.00 1.89 -1.89 † †
4 K031004 0.57 -0.34 0.00 † † † †
5 K031005 0.45 1.71 0.00 0.93 -0.93 † †
6 K031006 0.62 -0.03 0.00 0.29 -0.29 † †
7 K031007 0.43 0.75 0.00 -0.08 0.08 † †
S8 1 K104201 0.53 -2.28 0.22 † † † †
2 K103301 0.80 2.48 0.21 † † † †
3 K103401 1.22 -0.10 0.20 † † † †
4 K103601 1.39 -0.20 0.19 † † † †
5 K103701 0.81 0.27 0.16 † † † †
6 K104001 1.28 -0.76 0.30 † † † †
8 K104301 0.86 0.53 0.30 † † † †
9 K103801 0.92 0.68 0.28 † † † †
10 K103901 0.29 2.21 0.00 † † † †
11 K104101 1.13 0.79 0.23 † † † †
12 K103001 0.94 1.11 0.15 † † † †
13 K103101 0.66 3.26 0.00 † † † †
14 K103201 0.21 4.18 0.28 † † † †
15 K102801 1.12 1.06 0.25 † † † †
16 K102901 0.77 0.84 0.20 † † † †
S9 1 K031601 0.87 -0.08 0.28 † † † †
2 K031602 0.52 0.88 0.00 0.17 -0.17 † †
3 K031603 0.44 -1.43 0.00 0.02 -0.02 † †
4 K031604 0.38 3.33 0.00 1.60 -1.60 † †
6 K031606 0.37 2.84 0.00 1.93 -1.93 † †
7 K031607 0.94 0.06 0.00 † † † †
8 K031608 0.52 3.19 0.00 2.42 -2.42 † †
9 K031609 0.64 2.01 0.00 -0.22 0.22 † †
S10 1 K031701 0.59 -0.30 0.25 † † † †
9 K0325CL 0.40 -0.43 0.00 -0.44 -1.32 1.76 †
10 K032601 0.77 1.28 0.00 0.87 -0.87 † †
11 K032602 0.75 1.41 0.00 † † † †
S11 1 K099201 0.40 -2.32 0.26 † † † †
5 K098001 0.79 -1.19 0.28 † † † †
11 K092201 0.82 1.04 0.00 0.40 -0.40 † †
S12 4 K033901 0.73 0.49 0.26 † † † †
S13 1 K034601 0.24 0.18 0.24 † † † †
2 K034701 1.17 1.80 0.35 † † † †
S14 2 K035501 0.38 -1.00 0.25 † † † †
6 K035901 0.54 2.36 0.00 † † † †
S15 1 K037001 0.88 1.15 0.16 † † † †
2 K037101 0.48 -0.95 0.23 † † † †
3 K037201 1.17 0.86 0.29 † † † †
S20 1 K099101 0.42 -1.56 0.24 † † † †
4 K090101 0.41 -1.93 0.24 † † † †
7 K098101 0.59 0.55 0.20 † † † †
S21 5 K039901 0.43 -1.09 0.00 3.33 -1.00 -1.62 -0.72
8 K040201 0.99 1.86 0.13 † † † †
† 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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