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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 8 Science State Assessment (Accommodations Permitted [R3]): 2000
NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 8 science state assessment (accommodations permitted [R3]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3
S6 10 K031307 0.91 1.59 0.00 0.61 -0.61 †
11 K031308 0.61 2.57 0.00 † † †
S8 1 K041301 0.80 -2.29 0.24 † † †
2 K041302 1.04 -1.30 0.37 † † †
3 K041303 0.71 -1.25 0.17 † † †
4 K041304 0.57 -0.08 0.10 † † †
5 K041305 1.43 -0.63 0.21 † † †
6 K041306 0.72 -0.59 0.00 † † †
7 K041307 0.39 1.91 0.00 -0.36 0.36 †
8 K041401 0.89 0.69 0.00 1.04 -1.04 †
9 K041402 1.02 1.69 0.00 1.26 -1.26 †
10 K041403 0.37 2.48 0.00 1.26 -1.26 †
S9 1 K031601 0.94 -1.43 0.33 † † †
2 K031602 0.43 -0.42 0.00 0.61 -0.61 †
3 K031603 0.75 -1.49 0.00 † † †
4 K031604 0.54 0.74 0.00 † † †
5 K031605 0.41 -0.70 0.35 † † †
6 K031606 0.42 1.04 0.00 1.47 -1.47 †
7 K031610 0.73 0.26 0.00 1.43 -1.43 †
8 K031607 0.49 -0.65 0.00 0.20 0.97 -1.17
9 K031608 0.57 1.69 0.00 1.91 -1.91 †
10 K031609 0.47 0.52 0.00 † † †
11 K031611 0.37 2.20 0.00 † † †
12 K031612 0.98 -0.06 0.39 † † †
13 K031613 0.58 2.42 0.00 -0.90 0.90 †
S10 1 K092301 0.85 -1.03 0.39 † † †
2 K098801 1.24 -0.03 0.20 † † †
5 K099001 0.48 -0.33 0.00 1.55 -1.55 †
8 K090601 1.22 0.27 0.18 † † †
17 K092901 0.59 1.32 0.16 † † †
18 K096101 0.78 1.27 0.00 1.05 -1.05 †
19 K090701 0.47 1.22 0.34 † † †
20 K098901 0.63 0.25 0.24 † † †
S11 6 K043001 0.25 4.09 0.00 1.00 -1.00 †
12 K043401 0.29 -0.40 0.25 † † †
S12 8 K047501 0.21 4.21 0.25 † † †
10 K047701 1.02 2.44 0.15 † † †
11 K047801 1.01 1.20 0.17 † † †
13 K048001 0.89 1.02 0.00 1.73 -1.73 †
14 K048101 0.53 1.45 0.00 0.27 -1.09 0.83
15 K048102 0.76 3.72 0.00 1.12 -1.12 †
16 K048103 0.57 0.65 0.00 † † †
S13 3 K048401 0.65 0.78 0.25 † † †
8 K048901 0.52 0.45 0.00 0.42 -0.42 †
11 K049201 0.26 0.23 0.20 † † †
12 K049301 0.21 6.49 0.00 † † †
S14 2 K035501 0.60 -1.63 0.28 † † †
6 K035901 0.67 0.95 0.00 † † †
12 K036501 1.06 0.96 0.35 † † †
14 K036701 0.40 2.74 0.00 -0.81 0.81 †
15 K036801 0.52 1.38 0.00 -0.42 0.42 †
S15 2 K037101 0.28 -2.64 0.20 † † †
3 K037201 0.73 -1.06 0.20 † † †
12 K038001 0.90 1.47 0.23 † † †
13 K038002 1.16 1.26 0.18 † † †
14 K038101 0.65 2.52 0.00 † † †
S20 1 K093001 0.76 -1.10 0.34 † † †
12 K090201 0.78 -0.19 0.24 † † †
13 K092801 0.62 3.43 0.00 † † †
17 K091601 0.88 1.56 0.23 † † †
18 K094901 0.56 3.11 0.00 1.40 -1.40 †
19 K095001 0.65 0.67 0.23 † † †
20 K091201 1.90 1.15 0.24 † † †
S21 1 K045201 0.64 -1.66 0.28 † † †
2 K045301 0.30 3.82 0.00 † † †
5 K045601 0.60 1.66 0.00 0.93 -0.93 †
9 K046001 0.34 0.09 0.10 † † †
12 K046301 0.37 1.67 0.00 2.58 -2.58 †
13 K046401 0.70 1.83 0.00 † † †
16 K046701 0.66 1.08 0.00 1.77 -1.18 -0.59
† 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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