Modern Intraclass Correlation Coefficients R package intraclass version 0.1.0 Estimates interrater-reliability intraclass correlation coefficients (ICCs) within the generalizability-theory framework using modern variance-component estimation (linear mixed models) rather than the classical analysis-of-variance mean-squares approach. Provides the full ICC family (absolute agreement versus consistency, single versus average, fixed versus random raters, one-way versus two-way) with boundary-aware Monte-Carlo confidence intervals, support for imbalanced, incomplete, and multilevel (nested) designs, decision-study projection to other numbers of raters, and an interactive helper for choosing the correct coefficient. Multilevel methods follow ten Hove, Jorgensen and van der Ark (2022) <doi:10.1037/met0000391>. Software Depends: R (>= 4.5.0) Imports: cli, generics, glmmTMB, lifecycle, rlang, stats, tibble Suggests: brms, coda, covr, ggplot2, irr, irrICC, knitr, lavaan, lme4, merDeriv, posterior, psych, rmarkdown, spelling, testthat (>= 3.0.0), withr Jeffrey Girard <me@jmgirard.com> Comprehensive R Archive Network (CRAN) Jeffrey Girard [aut, cre] (ORCID: <https://orcid.org/0000-0002-7359-3746>) MIT + file LICENSE (https://CRAN.R-project.org/package=intraclass/LICENSE) 2026-09-10 application/tgz https://CRAN.R-project.org/package=intraclass doi:10.32614/CRAN.package.intraclass en-US