Exact Nonparametric Sensitivity Analysis for I by J Contingency Tables R package sensitivityIxJ version 0.1.5 Implements exact, normally approximated, and sampling-based sensitivity analysis for observational studies with contingency tables. Includes exact (kernel-based), normal approximation, and sequential importance sampling (SIS) methods using 'Rcpp' for computational efficiency. The methods build upon the framework introduced in Rosenbaum (2002) <doi:10.1007/978-1-4757-3692-2> and the generalized design sensitivity framework developed by Chiu (2025) <doi:10.48550/arXiv.2507.17207>. Software Imports: Rcpp LinkingTo: Rcpp Suggests: rbounds Elaine Chiu <kchiu4@wisc.edu> Comprehensive R Archive Network (CRAN) Elaine Chiu [aut, cre] GPL-3 2025-10-16 application/tgz https://CRAN.R-project.org/package=sensitivityIxJ doi:10.32614/CRAN.package.sensitivityIxJ