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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 Not Permitted [R2]): 2000
NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 8 science state assessment (accommodations not permitted [R2]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3
S6 10 K031307 0.88 1.59 0.00 0.62 -0.62 †
11 K031308 0.58 2.66 0.00 † † †
S8 1 K041301 0.80 -2.37 0.23 † † †
2 K041302 1.00 -1.38 0.38 † † †
3 K041303 0.68 -1.36 0.18 † † †
4 K041304 0.56 -0.15 0.10 † † †
5 K041305 1.36 -0.76 0.18 † † †
6 K041306 0.69 -0.70 0.00 † † †
7 K041307 0.39 1.88 0.00 -0.38 0.38 †
8 K041401 0.84 0.67 0.00 1.09 -1.09 †
9 K041402 0.97 1.72 0.00 1.32 -1.32 †
10 K041403 0.35 2.54 0.00 1.31 -1.31 †
S9 1 K031601 0.92 -1.55 0.32 † † †
2 K031602 0.41 -0.51 0.00 0.65 -0.65 †
3 K031603 0.73 -1.56 0.00 † † †
4 K031604 0.52 0.72 0.00 † † †
5 K031605 0.38 -0.94 0.32 † † †
6 K031606 0.42 0.99 0.00 1.49 -1.49 †
7 K031610 0.71 0.22 0.00 1.46 -1.46 †
8 K031607 0.48 -0.70 0.00 0.17 1.00 -1.17
9 K031608 0.54 1.70 0.00 1.99 -1.99 †
10 K031609 0.49 0.47 0.00 † † †
11 K031611 0.37 2.17 0.00 † † †
12 K031612 0.91 -0.23 0.35 † † †
13 K031613 0.55 2.46 0.00 -0.93 0.93 †
S10 1 K092301 0.81 -1.18 0.36 † † †
2 K098801 1.19 -0.08 0.20 † † †
5 K099001 0.46 -0.38 0.00 1.61 -1.61 †
8 K090601 1.13 0.20 0.17 † † †
17 K092901 0.58 1.31 0.17 † † †
18 K096101 0.80 1.24 0.00 1.05 -1.05 †
19 K090701 0.38 0.97 0.28 † † †
20 K098901 0.61 0.26 0.26 † † †
S11 6 K043001 0.23 4.33 0.00 1.11 -1.11 †
12 K043401 0.25 -0.55 0.25 † † †
S12 8 K047501 0.18 4.25 0.22 † † †
10 K047701 1.06 2.39 0.15 † † †
11 K047801 0.97 1.19 0.17 † † †
13 K048001 0.85 1.00 0.00 1.81 -1.81 †
14 K048101 0.52 1.45 0.00 0.30 -1.15 0.85
15 K048102 0.78 3.62 0.00 1.11 -1.11 †
16 K048103 0.53 0.61 0.00 † † †
S13 3 K048401 0.69 0.79 0.26 † † †
8 K048901 0.50 0.42 0.00 0.41 -0.41 †
11 K049201 0.26 0.16 0.20 † † †
12 K049301 0.19 7.03 0.00 † † †
S14 2 K035501 0.57 -1.71 0.30 † † †
6 K035901 0.65 0.95 0.00 † † †
12 K036501 1.05 0.96 0.36 † † †
14 K036701 0.40 2.73 0.00 -0.82 0.82 †
15 K036801 0.51 1.39 0.00 -0.40 0.40 †
S15 2 K037101 0.26 -2.86 0.21 † † †
3 K037201 0.75 -1.05 0.22 † † †
12 K038001 0.93 1.48 0.24 † † †
13 K038002 1.17 1.29 0.19 † † †
14 K038101 0.66 2.47 0.00 † † †
S20 1 K093001 0.71 -1.28 0.29 † † †
12 K090201 0.76 -0.30 0.21 † † †
13 K092801 0.58 3.59 0.00 † † †
17 K091601 0.82 1.56 0.22 † † †
18 K094901 0.54 3.15 0.00 1.42 -1.42 †
19 K095001 0.65 0.71 0.25 † † †
20 K091201 1.88 1.13 0.24 † † †
S21 1 K045201 0.65 -1.53 0.37 † † †
2 K045301 0.29 3.90 0.00 † † †
5 K045601 0.58 1.66 0.00 0.95 -0.95 †
9 K046001 0.30 0.09 0.11 † † †
12 K046301 0.35 1.71 0.00 2.71 -2.71 †
13 K046401 0.68 1.83 0.00 † † †
16 K046701 0.64 1.07 0.00 1.81 -1.20 -0.60
† 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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