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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 National Main Assessment (Accommodations Not Permitted [R2]): 2000
NAEP Technical DocumentationIRT parameters for the life science scale, by block and item, grade 8 science national main assessment (accommodations not permitted [R2]): 2000
Block Item NAEP ID aj bj cj dj1 dj2 dj3
S6 10 K031307 0.99 1.62 0.00 0.78 -0.78 †
11 K031308 0.56 2.51 0.00 † † †
S8 1 K041301 0.80 -2.39 0.22 † † †
2 K041302 0.94 -1.49 0.29 † † †
3 K041303 0.71 -1.12 0.20 † † †
4 K041304 0.61 0.06 0.13 † † †
5 K041305 1.28 -0.72 0.22 † † †
6 K041306 0.65 -0.70 0.00 † † †
7 K041307 0.42 1.72 0.00 -0.36 0.36 †
8 K041401 0.83 0.69 0.00 1.07 -1.07 †
9 K041402 1.02 1.60 0.00 1.20 -1.20 †
10 K041403 0.33 2.90 0.00 1.50 -1.50 †
S9 1 K031601 0.80 -1.87 0.24 † † †
2 K031602 0.37 -0.48 0.00 0.63 -0.63 †
3 K031603 0.67 -1.55 0.00 † † †
4 K031604 0.50 0.74 0.00 † † †
5 K031605 0.45 -1.27 0.25 † † †
6 K031606 0.46 1.00 0.00 1.31 -1.31 †
7 K031610 0.65 0.19 0.00 1.44 -1.44 †
8 K031607 0.49 -0.71 0.00 0.35 0.87 -1.22
9 K031608 0.53 1.72 0.00 1.95 -1.95 †
10 K031609 0.49 0.53 0.00 † † †
11 K031611 0.29 2.93 0.00 † † †
12 K031612 1.06 -0.05 0.39 † † †
13 K031613 0.64 2.27 0.00 -1.00 1.00 †
S10 1 K092301 0.79 -1.40 0.24 † † †
2 K098801 1.22 0.00 0.23 † † †
8 K090601 1.06 0.21 0.17 † † †
17 K092901 0.58 1.29 0.19 † † †
18 K096101 0.79 1.29 0.00 1.10 -1.10 †
19 K090701 0.33 0.71 0.24 † † †
20 K098901 0.44 0.21 0.22 † † †
5 K099001 0.51 -0.33 0.00 1.64 -1.64 †
S11 6 K043001 0.27 3.45 0.00 0.82 -0.82 †
12 K043401 0.27 -0.51 0.24 † † †
S12 8 K047501 0.48 3.05 0.31 † † †
10 K047701 0.94 2.57 0.16 † † †
11 K047801 0.98 1.13 0.17 † † †
13 K048001 0.88 0.93 0.00 1.76 -1.76 †
14 K048101 0.57 1.48 0.00 0.44 -1.05 0.60
15 K048102 0.75 3.84 0.00 1.31 -1.31 †
16 K048103 0.51 0.84 0.00 † † †
S13 3 K048401 0.64 0.74 0.23 † † †
8 K048901 0.49 0.37 0.00 0.34 -0.34 †
11 K049201 0.16 0.49 0.25 † † †
12 K049301 0.31 4.26 0.00 † † †
S14 2 K035501 0.55 -1.73 0.23 † † †
6 K035901 0.60 0.97 0.00 † † †
12 K036501 1.12 0.99 0.37 † † †
14 K036701 0.46 2.58 0.00 -0.54 0.54 †
15 K036801 0.52 1.35 0.00 -0.43 0.43 †
S15 2 K037101 0.24 -2.92 0.24 † † †
3 K037201 0.72 -1.08 0.24 † † †
12 K038001 0.89 1.69 0.23 † † †
13 K038002 1.42 1.27 0.18 † † †
14 K038101 0.62 2.55 0.00 † † †
S20 1 K093001 0.72 -1.29 0.26 † † †
12 K090201 0.80 -0.26 0.25 † † †
13 K092801 0.63 3.25 0.00 † † †
17 K091601 0.63 1.85 0.19 † † †
18 K094901 0.51 3.27 0.00 1.59 -1.59 †
19 K095001 0.59 0.50 0.22 † † †
20 K091201 1.36 0.99 0.22 † † †
S21 1 K045201 0.58 -1.71 0.25 † † †
2 K045301 0.34 3.17 0.00 † † †
5 K045601 0.58 1.66 0.00 0.94 -0.94 †
9 K046001 0.39 0.33 0.14 † † †
12 K046301 0.29 2.11 0.00 3.66 -3.66 †
13 K046401 0.64 1.85 0.00 † † †
16 K046701 0.53 1.19 0.00 2.21 -1.51 -0.70
† 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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