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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 Univariate Science Scale, Grade 8 Science Combined National and State Main Assessment, by Item and Block: 2009

NAEP Technical DocumentationIRT parameters for items in the univariate 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: Univariate scale. 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 0.52 -0.49 0.37
2 K114101 1.15 1.41 0.34
3 K113901 0.53 -0.18 0.99 -0.99
4 K114001 0.91 0.15 0.28
5 K114002 0.74 0.41 0.18
6 K113401 0.36 0.71 -0.04 -0.10 2.26 -2.11
7 K113201 0.35 -0.68 2.30 -1.81 -0.49
8 K113102 0.59 0.88 0.30
11 K113603 0.45 0.72 0.10
12 K113001 1.07 -0.13 0.33
13 K113801 0.69 0.27 0.34
14 K113701 0.49 0.40 0.25 0.17 -0.42
15 K134201 0.47 -0.02 -0.37 -0.12 0.49
16 K113301 0.93 0.92 0.36
17 K113501 0.60 0.34 0.24
S4 1 K117801 1.26 -0.62 0.36
2 K114601 0.45 0.18 -0.22 0.43 -0.22 0.01
3 K122201 1.56 0.84 0.34
4 K122301 0.64 0.61 0.19
5 K122302 1.13 0.44 0.41
6 K122303 1.27 1.56 0.29
7 K122304 1.57 0.85 0.23
8 K116701 1.49 1.10 0.32
9 K122901 0.86 -0.45 0.24
10 K118901 1.02 -0.57 0.30
11 K122402 0.50 1.56 1.13 -1.13
12 K123001 0.66 0.42 0.21
13 K122801 0.69 1.46 0.56 -0.56
14 K122001 1.17 0.63 0.26
15 K122602 0.45 1.05 -0.15 0.15
16 K125201 0.34 0.38 0.07 0.81 -1.57 0.69
17 K122501 0.42 0.30 0.20
18 K121801 1.19 1.61 0.24
S5 1 K120701 1.23 0.44 0.54
2 K120601 1.85 1.58 0.29
3 K154501 1.01 0.11 0.24
4 K121701 0.45 3.00 0.28
5 K121301 0.54 2.06 -0.36 -0.01 0.36
6 K117601 0.84 1.60 0.32
7 K120801 1.10 0.91 0.18
8 K120802 0.34 1.54 0.25 -0.25
9 K118501 0.52 1.19 1.31 -0.07 -1.25
10 K154601 0.49 0.45 0.78 -0.78
11 K120901 1.02 0.52 0.23
12 K121401 1.06 0.63 0.53
13 K121402 0.83 0.00 0.30
14 K121403 2.24 1.42 0.10
15 K154701 0.62 0.58 2.27 -1.11 -1.16
16 K154801 1.01 -0.58 0.30
17 K121201 1.05 -0.14 0.27
18 K120501 1.47 0.04 0.29
S6 1 K125101 0.38 -1.24 0.24
2 K124501 1.44 0.78 0.27
3 K124601 0.72 1.69 0.30
4 K123801 0.66 0.56 0.41 0.02 -0.43
5 K123802 0.42 0.41 0.67 -0.67
6 K154901 0.61 0.67 0.25
7 K122101 0.49 1.31 0.76 1.85 -2.61
8 K125001 0.71 1.46 0.29
9 K125002 0.98 0.85 0.30
10 K125003 0.36 0.91 0.78 -0.78
11 K155001 1.57 -0.25 0.35
12 K155101 1.27 1.40 0.21
13 K155201 1.04 0.38 0.23
14 K125401 0.45 1.91 1.97 -1.97
15 K125402 0.49 0.51 0.58 -0.58
16 K155301 1.49 0.63 0.39
17 K124401 1.19 0.33 0.33
S7 1 K111301 1.40 1.20 0.32
2 K117401 1.28 0.77 0.13
3 K155401 0.72 0.04 0.19
4 K1107CL 0.60 -0.42 1.65 -0.06 -1.59
5 K114501 1.61 1.46 0.17
6 K110601 1.10 -0.82 0.30
7 K110602 0.82 0.27 0.23
8 K110603 1.74 1.38 0.28
9 K123901 0.54 0.71 1.34 1.43 -0.50 -2.27
10 K110401 0.40 1.15 -0.41 0.57 -0.16
12 K110501 0.71 1.37 1.00 -1.00
13 K121001 0.83 1.50 0.29 -0.29
14 K1210CL 0.40 0.50 -0.84 1.87 -1.04
15 K110801 1.08 1.56 0.25
16 K110101 1.44 1.49 0.33
S8 1 K112801 1.03 -0.39 0.38
2 K112501 0.35 0.40 0.22
3 K111901 0.79 1.57 0.45
4 K155501 1.03 0.47 0.14
5 K155502 1.19 0.38 0.18
6 K112401 0.64 1.25 -0.52 -2.22 2.74
7 K112001 1.37 0.59 0.16
8 K119701 1.35 0.63 0.26
9 K155601 0.28 2.57 -1.82 1.45 2.10 -1.73
10 K117201 0.72 0.44 0.30
11 K117202 0.53 -0.25
12 K155701 0.60 1.71 0.43 -0.43
13 K155702 0.70 2.02 1.00 -1.00
14 K111601 0.76 0.29 0.19
15 K112901 0.84 1.57 0.23
16 K155801 1.43 -0.17 0.32
17 K112701 0.71 0.53 0.26
18 K155901 0.66 0.19 0.30
S9 1 K115101 0.86 -0.09 0.32
2 K114401 1.13 0.54 0.17
3 K115201 0.72 0.79 0.18 0.76 -0.94
4 K114901 1.18 0.41 0.23
5 K1560CL 0.25 2.76 2.56 -2.56
6 K156101 0.45 1.97 -1.94 1.86 0.08
7 K115501 1.65 1.60 0.16
8 K114802 0.61 0.26 -0.33 0.33
9 K114801 0.37 1.91 -1.21 2.53 -1.32
10 K115301 1.01 -0.28 0.32
12 K124102 0.51 0.61 0.67 -0.67
13 K111401 0.92 1.57 0.30
1 K156201 1.11 0.77 0.40
S10 1 K116401 0.77 -0.45 0.33
2 K111701 0.99 0.82 0.32
3 K123501 0.39 -1.03 0.11
4 K156301 0.87 1.41 0.20
5 K115801 0.88 -0.01 0.27
6 K1158CL 0.67 -1.95 0.78 -0.78
7 K1564CL 1.05 -0.90
8 K156601 0.86 -0.41 0.31
9 K110901 0.68 1.56 0.08 -0.08
10 K116101 0.46 1.17 0.89 1.97 -1.38 -1.49
11 K116001 1.19 1.72 0.26
12 K116002 0.93 -0.30
13 K116201 0.86 0.16 0.21
14 K116202 0.61 1.63 1.04 1.49 -2.53
15 K117301 1.08 1.04 0.28
16 K1159CL 0.67 1.56 1.97 0.39 -1.39 -0.96
17 K115701 0.67 -0.46 0.23
S11 1 K119401 0.99 -0.07 0.34
2 K123201 0.65 0.69 0.26
3 K119201 1.03 0.80 0.33
4 K156701 0.70 2.23 0.20
5 K123601 0.37 -0.44 1.37 -3.27 2.11 -0.21
6 K111801 1.04 0.88 0.49 -0.49
7 K111802 0.81 0.81 -0.08 0.08
8 K111803 0.72 1.64 0.31 -0.31
9 K120101 1.41 1.18 0.13
10 K117001 0.51 1.04 0.49 -0.49
11 K1170CL 0.42 1.58 -0.06 -0.14 0.20
12 K117005 0.79 -0.65 0.39
13 K117006 1.43 1.06 0.30
14 K119902 0.48 1.63 1.78 -1.78
15 K120301 0.81 0.65 0.25
16 K119601 0.73 1.31 0.32
S12 1 K118001 0.87 -0.17 0.36
2 K156801 1.33 0.64 0.18
3 K156901 1.37 1.51 0.24
4 K118601 0.97 1.05 0.14
5 K124001 0.75 0.16 0.29
6 K116901 0.51 -0.44 -0.16 0.16
7 K123301 0.80 0.08
8 K157001 0.64 1.06 1.30 -1.30
9 K119505 1.05 0.28
10 K124301 0.41 1.43 0.08
11 K123401 0.65 0.44 0.24 -0.40 0.16
12 K112601 0.76 2.02 0.78 -0.78
13 K118801 0.63 0.78 0.17
14 K157101 0.94 0.95 0.33
15 K115601 0.94 0.36 0.31

Last updated 03 June 2016 (GF)