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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 Life Science Scale, Grade 12 Science National Main Assessment, by Item and Block: 2009

NAEP Technical DocumentationIRT parameters for items in the life science scale, grade 12 science national 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 2 K126501 0.38 -0.75 0.25
7 K139001 0.82 0.62 1.01 -1.01
9 K126301 1.28 1.01 0.31
10 K126302 1.84 0.60 0.19
11 K126303 0.53 1.42 -0.68 1.55 0.48 -1.36
12 K126304 1.36 0.29
S4 1 K137501 0.68 -2.45 0.24
7 K137201 0.43 1.54 -0.41 -0.28 0.69
8 K137202 0.81 -0.08 0.30
14 K126801 1.08 0.75 0.19
17 K134801 1.13 0.10 0.22
S5 2 K129601 0.90 1.34 0.48 -0.48
3 K129602 0.96 0.06 0.34
11 K132301 1.99 1.75 0.26
12 K132302 0.81 0.91 0.22
13 K132303 2.37 1.24 0.13
14 K132304 0.56 -0.86 0.24
16 K136701 0.79 0.33 0.27
S6 1 K158101 1.93 0.52 0.27
6 K139801 0.51 0.53 0.33 -0.33
10 K143801 0.87 2.50 0.61 -0.61
13 K134501 1.52 1.06 0.16
14 K134502 1.02 0.05 0.25
15 K134503 0.61 2.46
S7 2 K135601 0.52 -0.57 0.20
8 K132701 1.41 1.62 0.40 -0.40
9 K142701 0.83 1.08 0.21
10 K142703 1.18 0.38 0.25
11 K142704 1.41 1.39 0.17
12 K135401 0.43 0.35 -0.07 0.07
15 K137801 0.74 -0.38 0.28
17 K142201 0.73 -0.20 0.21
S8 1 K136201 1.93 0.78 0.17
3 K127201 0.44 -0.16 1.16 1.39 -0.91 -1.65
7 K136401 0.85 1.35 -0.14 0.14
8 K134001 1.55 1.10 0.18
14 K136901 1.44 0.89 0.34
15 K139201 2.63 1.31 0.31
17 K128801 0.58 -1.91 0.24
S9 5 K131101 0.61 1.13 0.37
6 K131102 0.80 -0.61 0.23
7 K131103 0.45 1.09 -0.34 0.34
11 K138101 0.98 1.14 0.25
14 K138401 1.43 1.38 0.94 -0.94
15 K138402 1.01 1.87 0.75 -0.26 -0.49
S10 2 K129401 0.53 -0.48 0.25
4 K141501 0.92 -1.00 0.23
5 K1585CL 0.53 2.11 2.29 1.02 -3.31
6 K141503 1.13 1.55 0.37 -0.37
10 K130401 0.47 -0.74 0.28
11 K130402 2.74 1.77 0.17
S11 1 K136001 0.42 -0.76 0.22
5 K127701 0.42 0.78 1.52 0.09 -1.61
11 K144201 1.50 1.29 0.11
12 K144202 0.84 1.44 0.29 -0.29
14 K139601 0.77 1.34 0.23
S12 1 K143101 1.23 0.56 0.25
4 K129001 0.95 2.83 0.85 -0.85
7 K133401 0.38 1.62 1.35 -1.35
9 K142901 0.96 1.28 0.15
12 K127401 1.10 -0.85 0.16
14 K127403 0.84 -0.73 0.18
16 K130101 0.91 0.45 0.26
S13 1 K143401 0.72 1.37 0.20
5 K140301 0.57 1.13 0.67 -0.67
6 K1587CL 0.60 1.55 0.73 2.01 -2.74
7 K140303 0.73 0.10 -0.01 0.01
8 K142001 0.76 1.83 0.23
14 K129201 0.93 0.25 0.24
16 K138601 1.56 1.05 0.26

Last updated 03 June 2016 (GF)