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Table 1 Simulation conditions. The conditions of the full cross classified design for the simulation study. The numbers of items, number of participants, as well as the skewness from a normal distribution of the latent variable were varied

From: Why item response theory should be used for longitudinal questionnaire data analysis in medical research

Modela Itemsb Nc Skewness
IRT 3 100 0
CTT 5 500 +/− 0.4
  7 1000 +/− 0.8
  10   +/− 1.3
  15   +/− 1.9
  20   +/− 2.6
  50   +/− 3.6
  1. aMeasurement model that was used for drawing the plausible values for the latent variable
  2. bNumber of items
  3. cNumber of participants