Improved Methods for Survival Analysis under Double Truncation R package survdt version 0.9.0 Contains existing and novel methods for nonparametric analysis and Cox regression analysis with doubly truncated survival data, as described in Vazquez and Xie (2025) <doi:10.1007/s10985-025-09650-5>. Includes survival curves and hazard estimates through nonparametric maximum likelihood estimation, various tests for detecting group differences or non-ignorable sampling bias, and inverse probability weighted Cox regression with several options of nonparametric weights. Also implements diagnostics for key modeling assumptions such as quasi-independent truncation and the positivity assumption. Closed-form standard errors are available for all estimates, i.e. bootstrapping is not required. Software Depends: R (>= 2.10) Imports: ggplot2, igraph, stats, survival Suggests: knitr, rmarkdown Omar Vazquez <omar.vazquez@pennmedicine.upenn.edu> Comprehensive R Archive Network (CRAN) Omar Vazquez [aut, cre, cph] (ORCID: <https://orcid.org/0009-0009-4137-3333>), Sharon X. Xie [ths] (ORCID: <https://orcid.org/0000-0002-7886-4103>) GPL (>= 3) 2026-05-06 application/tgz https://CRAN.R-project.org/package=survdt doi:10.32614/CRAN.package.survdt