lsirm12pl 2.0.0 (2026-02-03)

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)