Time to Event Outcome in Experimental Designs of Pre-Clinical Studies R package PDXpower version 1.0.5 Conduct simulation-based customized power calculation for clustered time to event data in a mixed crossed/nested design, where a number of cell lines and a number of mice within each cell line are considered to achieve a desired statistical power, motivated by Eckel-Passow and colleagues (2021) <doi:10.1093/neuonc/noab137> and Li and colleagues (2025) <doi:10.51387/25-NEJSDS76>. This package provides two commonly used models for powering a design, linear mixed effects and Cox frailty model. Both models account for within-subject (cell line) correlation while holding different distributional assumptions about the outcome. Alternatively, the counterparts of fixed effects model are also available, which produces similar estimates of statistical power. Software Depends: R (>= 3.5.0) Imports: nlme,ggplot2,ggpubr,frailtypack,stats, survival, parallel, ggplot2 Suggests: testthat (>= 3.0.0), spelling Shanpeng Li <lishanpeng0913@ucla.edu> Comprehensive R Archive Network (CRAN) Shanpeng Li [aut, cre], Gang Li [ctb] GPL (>= 2) 2025-12-15 application/tgz https://CRAN.R-project.org/package=PDXpower doi:10.32614/CRAN.package.PDXpower en-US