The Closure Principle Computational Approach Test R package CPCAT version 1.0.0 P-values and no/lowest observed (adverse) effect concentration values derived from the closure principle computational approach test (Lehmann, R. et al. (2015) <doi:10.1007/s00477-015-1079-4>) are provided. The package contains functions to generate intersection hypotheses according to the closure principle (Bretz, F., Hothorn, T., Westfall, P. (2010) <doi:10.1201/9781420010909>), an implementation of the computational approach test (Ching-Hui, C., Nabendu, P., Jyh-Jiuan, L. (2010) <doi:10.1080/03610918.2010.508860>) and the combination of both, that is, the closure principle computational approach test. Software Depends: R (>= 2.10) Imports: stats Suggests: knitr, rmarkdown, testthat (>= 3.0.0) René Lehmann <rene.lehmann82@t-online.de> Comprehensive R Archive Network (CRAN) René Lehmann [aut, cre] (ORCID: <https://orcid.org/0000-0003-4145-8272>) GPL (>= 3) 2024-07-02 application/tgz https://CRAN.R-project.org/package=CPCAT doi:10.32614/CRAN.package.CPCAT