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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → NAEP Assessment IRT Parameters → Reading Long-Term Trend Assessment IRT Parameters → IRT Parameters, Age 9 Reading Long-Term Trend Assessment, by Item and Block: 2008

NAEP Technical DocumentationIRT parameters, age 9 reading long-term trend assessment, by item and block: 2008
Block Item NAEP ID aj bj cj dj1 dj2 dj3
† Not applicable; c parameters are not estimated for generalized partial credit 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 is 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), 2008 Reading Long-Term Trend Assessment.
RA 1 N021101 1.87 0.18 0.25 † † †
2 N021102 1.61 -0.13 0.34 † † †
3 N021201 1.83 0.05 0.33 † † †
4 N021202 1.19 1.17 0.18 † † †
5 N021203 0.55 1.42 † 0.93 -0.17 -0.76
6 N021301 1.49 0.33 0.22 † † †
7 N021302 2.61 0.90 0.10 † † †
8 N021303 2.01 1.00 0.23 † † †
RB 1 N021401 0.68 0.13 0.37 † † †
2 N021402 0.80 0.59 0.18 † † †
3 N021403 1.66 1.28 0.21 † † †
4 N021501 1.85 -0.03 0.24 † † †
5 N021502 1.34 0.41 0.29 † † †
6 N021503 1.32 -0.32 0.22 † † †
7 N021601 1.58 -0.16 0.31 † † †
8 N021602 0.90 0.31 0.31 † † †
9 N021603 1.01 0.83 0.24 † † †
10 N021701 1.37 -0.83 0.28 † † †
RC 1 N021801 1.19 -0.01 0.31 † † †
2 N021802 1.35 1.33 0.40 † † †
3 N021803 0.48 0.58 † 2.33 -2.22 -0.11
4 N021901 1.89 -0.46 0.32 † † †
5 N022001 1.63 -0.06 0.25 † † †
6 N022002 1.40 -0.29 0.27 † † †
7 N022003 1.50 0.23 0.38 † † †
8 N022004 2.27 -0.17 0.25 † † †
RD 1 N022101 1.68 -0.16 0.32 † † †
2 N022102 2.41 1.01 0.17 † † †
3 N022103 0.68 1.48 † 1.97 -0.13 -1.84
4 N022201 1.05 0.91 0.34 † † †
5 N022202 1.57 -0.49 0.28 † † †
6 N022203 1.53 0.09 0.23 † † †
7 N022204 2.03 0.58 0.20 † † †
8 N022205 2.06 0.52 0.20 † † †
RE 1 N022401 4.26 0.54 0.42 † † †
2 N022402 2.80 0.62 0.21 † † †
3 N022403 3.92 0.71 0.25 † † †
4 N022404 6.48 0.77 0.17 † † †
5 N022405 1.49 0.00 0.00 † † †
6 N022501 1.04 -0.20 0.34 † † †
7 N022601 0.65 -0.72 0.30 † † †
RF 1 N022701 1.20 -0.45 0.35 † † †
2 N022702 1.67 -0.14 0.21 † † †
3 N022703 1.49 -0.67 0.39 † † †
4 N022704 1.91 -0.31 0.19 † † †
5 N022801 1.24 -1.82 0.28 † † †
6 N022901 0.63 -1.81 0.21 † † †
7 N023001 1.12 0.08 0.16 † † †
8 N023002 1.47 0.63 0.27 † † †
9 N023101 1.36 0.64 0.27 † † †
10 N023102 1.49 0.57 0.24 † † †
RG 1 N023301 1.34 0.07 0.24 † † †
2 N023401 0.76 -0.78 0.29 † † †
3 N023402 1.73 0.28 0.30 † † †
4 N023403 0.94 -0.43 0.26 † † †
5 N023501 1.78 0.15 0.35 † † †
6 N023502 1.41 0.04 0.28 † † †
7 N023601 1.57 -0.17 0.38 † † †
8 N023602 0.98 -1.03 0.19 † † †
RH 1 N025901 1.05 -0.98 0.33 † † †
2 N026001 2.02 -0.05 0.22 † † †
3 N026002 1.44 -0.14 0.25 † † †
4 N026003 1.87 -0.66 0.24 † † †
5 N026101 1.37 0.64 0.16 † † †
6 N026102 1.73 0.96 0.32 † † †
7 N026201 1.44 -1.04 0.37 † † †
8 N026301 1.64 -0.41 0.21 † † †
9 N026302 1.03 -0.73 0.20 † † †
RI 1 N028601 1.61 -0.82 0.32 † † †
2 N028602 1.73 -0.63 0.27 † † †
3 N028701 1.79 -0.19 0.34 † † †
4 N028702 1.63 -0.11 0.24 † † †
5 N028703 1.12 -0.09 0.27 † † †
6 N028704 1.92 -0.63 0.23 † † †
7 N028801 1.25 0.23 0.21 † † †
8 N028802 0.97 0.49 0.26 † † †
9 N028901 1.05 0.40 0.30 † † †
10 N028902 1.50 1.11 0.22 † † †
RJ 1 N026901 1.40 0.37 0.26 † † †
2 N026902 1.74 -0.68 0.29 † † †
3 N027001 1.50 -0.49 0.19 † † †
4 N027002 1.25 -0.20 0.22 † † †
5 N027003 1.06 -0.78 0.22 † † †
6 N027101 1.50 0.06 0.25 † † †
7 N027102 1.09 0.07 0.32 † † †
8 N027201 1.43 0.48 0.14 † † †
9 N027202 1.70 -0.14 0.25 † † †
10 N027203 2.14 0.37 0.21 † † †
Last updated 09 July 2009 (JL)
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