Optimize PTSD Diagnostic Criteria R package PTSDdiag version 0.5.0 Provides tools for analyzing and optimizing PTSD (Post-Traumatic Stress Disorder) diagnostic criteria using PCL-5 (PTSD Checklist for DSM-5) and CAPS-5 (Clinician-Administered PTSD Scale for DSM-5) data. Functions identify optimal subsets of PCL-5 items that maintain diagnostic accuracy while reducing assessment burden. Includes tools for both hierarchical (cluster-based) and non-hierarchical symptom combinations, calculation of diagnostic metrics, and comparison with standard DSM-5 criteria. Redundancy analysis quantifies how many item subsets perform equivalently, through plateau sizes and bootstrap stability, and reports item selection against the chance baseline of the searched candidate space. A transport layer allows a site to evaluate subsets derived elsewhere and return only aggregate summaries, supporting multi-site validation without sharing individual-level data. Model validation is conducted using holdout and cross-validation methods to assess robustness and generalizability of the results. For more details see Weidmann et al. (2025) <doi:10.31219/osf.io/6rk72_v1>. Software Depends: R (>= 3.5.0) Imports: cli, dplyr, jsonlite, lifecycle, magrittr, rlang, rsample, stats, utils Suggests: DT, future.apply, ggplot2, knitr, rmarkdown, testthat (>= 3.0.0), withr Tobias R. Spiller <tobias.spiller@access.uzh.ch> Comprehensive R Archive Network (CRAN) Laura Weidmann [aut] (ORCID: <https://orcid.org/0009-0006-5509-6961>), Tobias R. Spiller [aut, cre] (ORCID: <https://orcid.org/0000-0002-0107-0743>), Flavio A. Schüepp [aut] (ORCID: <https://orcid.org/0000-0002-0750-3888>) MIT + file LICENSE (https://CRAN.R-project.org/package=PTSDdiag/LICENSE) 2026-08-04 application/tgz https://CRAN.R-project.org/package=PTSDdiag doi:10.32614/CRAN.package.PTSDdiag