IRT Scale Linking and Score Equating

  • Handles IRT linking for binary and polytomous items
  • Supported linking models include any combination of Rasch, 2PL, 3PL, PCM, RSM, GRM, or GPCM
  • Mean/mean, mean/sigma, Haebara, Stocking-Lord procedures
  • Fixed common item parameter estimation for Rasch, partial credit, and rating scale models
  • Robust z statistic for item parameter drift
  • Item parameter correlations
  • Save transformed person and item values to database
  • IRT true score equating using any combination of Rasch, 2PL, 3PL, PCM, RSM, GRM, or GPCM