Item Analysis in Rasch Models

Tools to assess model fit and identify misfitting items for Rasch models (RM) and partial credit models (PCM). Included are item fit statistics, item characteristic curves, item-restscore association, conditional likelihood ratio tests, assessment of measurement error, estimates of the reliability and test targeting as described in Christensen et al. (Eds.) (2013, ISBN:978-1-84821-222-0).


News for package 'iarm'

Changes in Version 0.2.0

  • bug fix for input arguments of partgam
  • added functions partgam_LD and partgam_DIF
  • person_estimates accepts now items with different number of levels, calculates person measures for all persons in the data set.
  • test_prop accepts pcmodel object as input.

Reference manual

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0.4.2 by Marianne Mueller, a year ago

Browse source code at

Authors: Marianne Mueller [aut, cre] , Pedro Henrique Ribeiro Santiago [ctb]

Documentation:   PDF Manual  

Task views: Psychometric Models and Methods

GPL-2 license

Imports gridExtra, Hmisc, PP, psychotools, stats, utils, vcdExtra

Depends on eRm, ggplot2

See at CRAN