Calibration, Validation, and Simulation of TKTD Models R package cvasi version 1.5.1 Eases the use of ecotoxicological effect models. Can simulate common toxicokinetic-toxicodynamic (TK/TD) models such as General Unified Threshold models of Survival (GUTS) and Lemna. It can derive effects and effect profiles (EPx) from scenarios. It supports the use of 'tidyr' workflows employing the pipe symbol. Time-consuming tasks can be parallelized. Software Depends: R (>= 3.5.0) Imports: cli, rlang, stringr, dplyr, tibble, purrr, furrr, tidyr, magrittr, utils, stats, methods, grid, gridExtra, ggplot2, GGally, deSolve, lubridate, units, lifecycle Suggests: future, knitr, lemna, rmarkdown, roxyglobals, testthat, withr Nils Kehrein <nils.kehrein@gmail.com> Comprehensive R Archive Network (CRAN) Nils Kehrein [aut, cre], Dirk Nickisch [aut], Peter Vermeiren [aut], Torben Wittwer [ctb], Johannes Witt [ctb], Andre Gergs [ctb] GPL (>= 3) 2026-04-11 application/tgz https://CRAN.R-project.org/package=cvasi doi:10.32614/CRAN.package.cvasi