The Short-Term and Long-Term Hazard Ratio Model for Survival Data R package YPmodel version 1.4 CRAN Task View: Survival (https://CRAN.R-project.org/view=Survival) Inference procedures accommodate a flexible range of hazard ratio patterns with a two-sample semi-parametric model. This model contains the proportional hazards model and the proportional odds model as sub-models, and accommodates non-proportional hazards situations to the extreme of having crossing hazards and crossing survivor functions. Overall, this package has four major functions: 1) the parameter estimation, namely short-term and long-term hazard ratio parameters; 2) 95 percent and 90 percent point-wise confidence intervals and simultaneous confidence bands for the hazard ratio function; 3) p-value of the adaptive weighted log-rank test; 4) p-values of two lack-of-fit tests for the model. See the included "read_me_first.pdf" for brief instructions. In this version (1.1), there is no need to sort the data before applying this package. Software Depends: R (>= 3.5.0) Junlong Sun <junlong.sun@gmail.com> Comprehensive R Archive Network (CRAN) Junlong Sun and Song Yang GPL (>= 3) 2020-10-19 application/tgz https://CRAN.R-project.org/package=YPmodel doi:10.32614/CRAN.package.YPmodel