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Table 2 Data description according to CTT

From: Item pre-knowledge true prevalence in clinical anatomy - application of gated item response theory model

YearPeriodNReused
(N)
Difficultya,c
Mean (SD)
Discriminationb,c
Mean (SD)
Cronbach’s Alphaωhωt
2008121700.57 (0.18)0.37 (0.19)0.880.460.89
212340.63 (0.20)0.32 (0.17)0.860.510.87
20091208130.66 (0.20)0.34 (0.13)0.880.480.88
211360.64 (0.21)0.37 (0.16)0.890.380.90
20101192260.64 (0.20)0.30 (0.14)0.860.440.87
2116130.59 (0.21)0.32 (0.15)0.870.410.88
20111243210.62 (0.22)0.37 (0.17)0.890.560.90
248140.59 (0.20)0.37 (0.19)0.900.360.91
  1. a% of students who correctly answered the item
  2. b Biserial correlation between the item and the number of correct answers to the other items
  3. c To assess whether there were significant differences between the examinations, in the difficulty and discrimination indexes, mixed effect models were used with a fixed factor (examination) and the item-level random intercept to account for the residual correlation within the same (reused) items