Analyzing Interval Data in Psychometrics R package intervalpsych version 0.1.0 Implements the Interval Consensus Model (ICM) for analyzing continuous bounded interval-valued responses in psychometrics using 'Stan' for 'Bayesian' estimation. Provides functions for transforming interval data to simplex representations, fitting item response theory (IRT) models with isometric log-ratio (ILR) and sum log-ratio (SLR) link functions, and visualizing results. The package enables aggregation and analysis of interval-valued response data commonly found in psychological measurement and related disciplines. Based on Kloft et al. (2024) <doi:10.31234/osf.io/dzvw2>. Software Depends: R (>= 4.1) Imports: dplyr, ggdist, ggokabeito, ggplot2, methods, posterior, purrr, Rcpp (>= 0.12.0), RcppParallel (>= 5.0.1), rstan (>= 2.18.1), rstantools (>= 2.4) LinkingTo: BH (>= 1.66.0), Rcpp (>= 0.12.0), RcppEigen (>= 0.3.3.3.0), RcppParallel (>= 5.0.1), rstan (>= 2.18.1), StanHeaders (>= 2.18.0) Suggests: testthat (>= 3.0.0) Matthias Kloft <kloft.dev+intervalpsych@gmail.com> Comprehensive R Archive Network (CRAN) Matthias Kloft [aut, cre, cph] (ORCID: <https://orcid.org/0000-0003-1845-6957>), Björn S. Siepe [aut] (ORCID: <https://orcid.org/0000-0002-9558-4648>) GPL (>= 3) 2025-07-08 application/tgz https://CRAN.R-project.org/package=intervalpsych doi:10.32614/CRAN.package.intervalpsych