Model Diagnostics for Accelerated Failure Time Models R package afttest version 4.5.3 A collection of model checking methods for semiparametric accelerated failure time (AFT) models under the rank-based approach. For the (computational) efficiency, Gehan's weight is used. It provides functions to verify whether the observed data fit the specific model assumptions such as a functional form of each covariate, a link function, and an omnibus test. The p-value offered in this package is based on the Kolmogorov-type supremum test and the variance of the proposed test statistics is estimated through the re-sampling method. Furthermore, a graphical technique to compare the shape of the observed residual to a number of the approximated realizations is provided. See the following references; A general model-checking procedure for semiparametric accelerated failure time models, Statistics and Computing, 34 (3), 117 <doi:10.1007/s11222-024-10431-7>; Diagnostics for semiparametric accelerated failure time models with R package 'afttest', arXiv, <doi:10.48550/arXiv.2511.09823>. Software Depends: R (>= 3.4.0) Imports: survival, aftgee, ggplot2, gridExtra LinkingTo: Rcpp, RcppArmadillo Suggests: knitr, rmarkdown, testthat (>= 3.0.0) Woojung Bae <matt.woojung@gmail.com> Comprehensive R Archive Network (CRAN) Woojung Bae [aut, cre] (ORCID: <https://orcid.org/0000-0001-6760-9900>), Dongrak Choi [aut] (ORCID: <https://orcid.org/0000-0003-3280-3329>), Jun Yan [aut] (ORCID: <https://orcid.org/0000-0003-4401-7296>), Sangwook Kang [aut] (ORCID: <https://orcid.org/0000-0003-2658-481X>) GPL (>= 3) 2026-03-22 application/tgz https://CRAN.R-project.org/package=afttest doi:10.32614/CRAN.package.afttest en-US