Screening, Trimming, and Aggregating Response Time Data R package rtprep version 0.1.0 A uniform interface to common response time preprocessing decisions that precede analysing aggregated response times or fitting an evidence accumulation model. Screening rules from different preprocessing routines -- absolute cutoffs, standard deviation and median absolute deviation criteria, recursive moving criteria, and model-based mixture flagging -- all return the same per-trial object, so that consequences of a preprocessing choice can be compared rather than assumed. The package also provides aggregation into EZ-diffusion summary statistics, diagnostics reporting what each rule removed and where rules disagree. Finally, generators for response time data with contaminants of known type are provided, so that a chosen pipeline can be tested against ground truth. Screening criteria follow Van Selst and Jolicoeur (1994) <doi:10.1080/14640749408401131>, the contaminant mixture Ratcliff and Tuerlinckx (2002) <doi:10.3758/BF03196302>, and the EZ-diffusion equations Wagenmakers, van der Maas and Grasman (2007) <doi:10.3758/BF03194023>. Software Depends: R (>= 4.1.0) Imports: graphics, stats, utils Suggests: testthat (>= 3.0.0), bmm, trimr, rtdists, SimDesign, dplyr, tibble, ggplot2, knitr, rmarkdown, spelling, withr Gidon T. Frischkorn <gfrischkorn@icloud.com> Comprehensive R Archive Network (CRAN) Gidon T. Frischkorn [aut, cre, cph] (ORCID: <https://orcid.org/0000-0002-5055-9764>) GPL (>= 2) 2026-10-05 application/tgz https://CRAN.R-project.org/package=rtprep doi:10.32614/CRAN.package.rtprep en-GB