Intraclass Correlation Coefficient (ICC) Design, Calculation and Interactive 'shiny' Toolkit R package ICCDesign version 0.1.0 A comprehensive toolkit for intraclass correlation coefficient (ICC) analysis, integrating three core functionalities: (1) Closed-form sample size calculation for ICC estimation with assurance probability, based on Zou (2012) <doi:10.1002/sim.5466>; (2) Full implementation of all 10 ICC types (6 common + 4 supplementary) for point estimation, exact confidence interval calculation, and formal hypothesis testing, following the methods of McGraw & Wong (1996) <doi:10.1037/1082-989X.1.1.30> and the standard decision framework; (3) An interactive 'shiny' application that guides users through ICC type selection, performs calculations, and provides reliability evaluation based on the Koo & Li (2016) <doi:10.1016/j.jcm.2016.02.012> criteria. Compared to existing packages, it provides a unified decision workflow and supports all less common ICC variants. Software Depends: R (>= 4.1.0) Imports: stats, shiny Suggests: testthat, knitr, rmarkdown Ziyu Liu <1755454769@qq.com> Comprehensive R Archive Network (CRAN) Ziyu Liu [aut, cre], Ruilin Ma [aut], Chenge Gao [aut], Yundan Zhang [aut] GPL (>= 3) 2026-05-27 application/tgz https://CRAN.R-project.org/package=ICCDesign doi:10.32614/CRAN.package.ICCDesign