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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Science Assessment IRT Parameters → IRT Parameters for Items in the Earth and Space Science Scale, Grade 8 Science Combined National and State Main Assessment, by Item and Block: 2009

NAEP Technical DocumentationIRT parameters for items in the earth and space science scale, grade 8 science combined national and state main assessment, by item and block: 2009
Block Item NAEP ID aj bj cj dj1 dj2 dj3 dj4
† Not applicable; c parameters are not estimated for generalized partial credit models, and d parameters are not estimated for two-parameter or three-parameter logistic models.
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 represents the category threshold parameter for category i. The c parameter value is exactly zero for items scaled with the two-parameter logistic model. For item j, dji may not sum to zero because of rounding.
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Science Assessment.
S3 1 K114201 0.48 -0.72 0.31 † † † †
2 K114101 0.98 1.44 0.33 † † † †
3 K113901 0.52 -0.19 † 1.00 -1.00 † †
8 K113102 0.42 0.64 0.21 † † † †
14 K113701 0.47 0.40 † 0.24 0.19 -0.43 †
16 K113301 0.86 0.93 0.36 † † † †
S4 3 K122201 1.79 0.83 0.35 † † † †
9 K122901 0.76 -0.63 0.19 † † † †
12 K123001 0.66 0.38 0.20 † † † †
15 K122602 0.43 1.07 † -0.17 0.17 † †
17 K122501 0.47 0.35 0.23 † † † †
18 K121801 1.17 1.61 0.24 † † † †
S5 1 K120701 1.23 0.42 0.54 † † † †
4 K121701 0.35 3.37 0.26 † † † †
5 K121301 0.54 2.10 † -0.32 -0.00 0.32 †
6 K117601 0.85 1.70 0.33 † † † †
7 K120801 1.10 0.95 0.19 † † † †
8 K120802 0.36 1.50 † 0.27 -0.27 † †
17 K121201 0.99 -0.25 0.23 † † † †
S6 1 K125101 0.39 -1.27 0.22 † † † †
7 K122101 0.42 1.27 † 0.62 1.35 0.12 -2.09
14 K125401 0.46 1.87 † 1.94 -1.94 † †
15 K125402 0.49 0.50 † 0.58 -0.58 † †
17 K124401 1.07 0.31 0.32 † † † †
S7 1 K111301 1.25 1.22 0.32 † † † †
4 K1107CL 0.57 -0.44 † 1.68 -0.05 -1.63 †
5 K114501 1.52 1.52 0.18 † † † †
7 K110602 0.77 0.23 0.22 † † † †
8 K110603 1.55 1.44 0.27 † † † †
10 K110401 0.40 1.16 † -0.42 0.59 -0.17 †
S8 2 K112501 0.35 0.46 0.23 † † † †
4 K155501 1.01 0.45 0.13 † † † †
5 K155502 1.22 0.39 0.18 † † † †
12 K155701 0.58 1.74 † 0.45 -0.45 † †
13 K155702 0.68 2.07 † 1.04 -1.04 † †
S9 1 K115101 0.80 -0.17 0.30 † † † †
3 K115201 0.67 0.80 † 0.16 0.82 -0.99 †
6 K156101 0.44 2.01 † -1.97 1.91 0.07 †
7 K115501 1.49 1.63 0.16 † † † †
13 K111401 0.96 1.52 0.29 † † † †
14 K156201 1.09 0.79 0.41 † † † †
S10 2 K111701 0.88 0.74 0.28 † † † †
3 K123501 0.38 -0.95 0.15 † † † †
4 K156301 0.85 1.46 0.20 † † † †
8 K156601 0.85 -0.49 0.28 † † † †
13 K116201 0.83 0.10 0.19 † † † †
14 K116202 0.58 1.67 † 1.08 1.55 -2.63 †
15 K117301 1.07 1.02 0.28 † † † †
16 K1159CL 0.62 1.64 † 2.09 0.43 -1.48 -1.03
S11 1 K119401 0.95 -0.15 0.31 † † † †
5 K123601 0.36 -0.44 † 1.36 -3.34 2.17 -0.19
6 K111801 1.49 0.27 † † † † †
7 K111802 0.98 0.77 † 0.01 -0.01 † †
8 K111803 0.74 1.64 † 0.33 -0.33 † †
9 K120101 1.31 1.21 0.13 † † † †
14 K119902 0.46 1.70 † 1.86 -1.86 † †
15 K120301 0.74 0.59 0.22 † † † †
16 K119601 0.60 1.31 0.29 † † † †
S12 1 K118001 0.84 -0.26 0.33 † † † †
3 K156901 1.34 1.53 0.24 † † † †
4 K118601 1.03 1.03 0.14 † † † †
5 K124001 0.60 -0.06 0.21 † † † †
6 K116901 0.47 -0.45 † -0.20 0.20 † †
10 K124301 0.45 1.40 0.10 † † † †
13 K118801 0.71 0.80 0.18 † † † †
14 K157101 0.99 0.92 0.32 † † † †
15 K115601 0.91 0.35 0.31 † † † †
Last updated 03 June 2016 (GF)
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