A Bayesian No-Effect- Concentration (NEC) Algorithm R package bayesnec version 2.1.3.1 CRAN Task View: Pharmacokinetics (https://CRAN.R-project.org/view=Pharmacokinetics) Implementation of No-Effect-Concentration estimation that uses 'brms' (see Burkner (2017)<doi:10.18637/jss.v080.i01>; Burkner (2018)<doi:10.32614/RJ-2018-017>; Carpenter 'et al.' (2017)<doi:10.18637/jss.v076.i01> to fit concentration(dose)-response data using Bayesian methods for the purpose of estimating 'ECx' values, but more particularly 'NEC' (see Fox (2010)<doi:10.1016/j.ecoenv.2009.09.012>), 'NSEC' (see Fisher and Fox (2023)<doi:10.1002/etc.5610>), and 'N(S)EC (see Fisher et al. 2023<doi:10.1002/ieam.4809>). A full description of this package can be found in Fisher 'et al.' (2024)<doi:10.18637/jss.v110.i05>. This package expands and supersedes an original version implemented in 'R2jags' (see Su and Yajima (2020)<https://CRAN.R-project.org/package=R2jags>; Fisher et al. (2020)<doi:10.5281/ZENODO.3966864>). Software Depends: R (>= 4.1), brms, ggplot2 Imports: formula.tools, loo, dplyr, tidyr, purrr, tibble, tidyselect, evaluate, rlang, chk (>= 0.7.0) Suggests: rstan, knitr, rmarkdown, testthat (>= 3.0.0) Rebecca Fisher <r.fisher@aims.gov.au> Comprehensive R Archive Network (CRAN) Rebecca Fisher [aut, cre] (ORCID: <https://orcid.org/0000-0001-5148-6731>), Diego R. Barneche [aut] (ORCID: <https://orcid.org/0000-0002-4568-2362>), Gerard F. Ricardo [aut] (ORCID: <https://orcid.org/0000-0002-2220-3971>), David R. Fox [aut] (ORCID: <https://orcid.org/0000-0002-3178-7243>) GPL-2 2025-08-19 application/tgz https://CRAN.R-project.org/package=bayesnec doi:10.32614/CRAN.package.bayesnec