NEWS

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lsirm12pl 2.0.0 (2026-02-04)

Major Changes

• NEW: Added Graded Response Model (GRM) for ordinal/Likert-scale data

  • lsirmgrm(): 1PL GRM with latent space
  • lsirmgrm2pl(): 2PL GRM with item discrimination parameters
  • Supports complete data, MAR, and MCAR missing data mechanisms
  • Implements threshold ordering constraint (β₁ > β₂ > ... > βₖ₋₁) for identifiability
  • Reference: De Carolis, Kang, & Jeon (2025), DOI: 10.1080/00273171.2025.2605678

• NEW: Adaptive MCMC algorithm

  • Automatic tuning of proposal standard deviations during burn-in
  • Parameter-specific target acceptance rates
  • Improved mixing and convergence for complex models
  • Available for all model types (1PL, 2PL, GRM)