• sim_gs_n() is updated to provide updated efficacy bound when it is one-sided design (#348, thanks to @LittleBeannie).
• The cut date driven by stratified targeted events is fixed in get_analysis_date() (#347, thanks to @LittleBeannie).

• Added an internal helper function cut_from_design() to automatically generate cuttings based on the design object (#350, thanks to @yihui).
• Updated significant digits required for sim_gs_n() test to verify the asymptotic theory from {gsDesign2} (#355, thanks to @jdblischak).

• A example of stratified group sequential design is added for the sim_gs_n() function (#336, #343, thanks to @LittleBeannie).

• The dplyr syntax in sim_gs_n() is replaced with data.table syntax for better speed (#339, thanks to @jdblischak).
• The parallelelly package version is temporarily downgraded to v1.44.0 for successful macOC build. (#341, #338, thanks to @jdblischak).

• Provide the updated boundary for objects generated by sim_gs_n() (#255, thanks to @LittleBeannie).
• Users can now pass a formula to call the wlr() function (#280, thanks to @jdblischak).
• wlr() is now a S3 class method for both tte_data class and counting_process class (@276, #280, @281, thanks to @jdblischak)
• The randomization ratio is output as attributes of sim_pw_surv() (#279, #311 thanks to @LittleBeannie and @jdblischak).

• Add 3 vignettes introducing simulation of fixed or group sequential design via a single function call of sim_fixed_n() and sim_gs_n() or from the ground up (#302, #316, thanks to @LittleBeannie).
• Add a vignette discussing the potential discrepancies between simtrial and survdiff (#308, thanks to @larry-leon).
• Update parallel vignette to address data.table multithreading (#319, thanks to @jdblischak).

• Optimize parallel simulation speed in sim_fixed_n() and sim_gs_n() by replacing foreach(.combine = "rbind") with manual data frame combination (#318, thanks to @nanxstats).

• Summary function of sim_gs_n() is available (#268, thanks to @LittleBeannie).
• The denominator of the milestone test Z-score is corrected (#270, thanks to @LittleBeannie).
• Statistical information is added as output of sim_gs_n() (#273, thanks to @LittleBeannie).
• The randomization ratio is built as an attribute of sim_pw_surv() and passed into the wlr() test (#281, #285 thanks to @LittleBeannie and @jdblischak).
• The sign of the Z-score is unified to positive numbers (#272, #286, thanks to @LittleBeannie and @jdblischak).

• The source code of summary() is rewritten from tibble or data.frame to data.table, which is optimized to use as little memory as possible by avoiding making unnecessary temporary copies of data frames. This results in code that is more efficient in both time and memory use. (#289, thanks to @jdblischak).
• The sim_fixed_n() function has been updated to allow parallel simulations (#249, #252, #253, #262, thanks to @cmansch and @jdblischak).

• Fixed the bug of cut functions in parallel (#261, thanks to @cmansch).

• The wlr() function is enhanced to S3 generic to accept both counting process and time-to-event data as its input (#276, #277, thanks to @jdblischak).

• Use KaTeX for pkgdown math rendering (#263, thanks to @nanxstats).

• Regression tests of summary() is added (#282, thanks to @jdblischak).

• Pass noSuggests checks by running code examples, tests, and vignettes conditionally if the Suggests dependencies are not installed (#243).

• rmst() introduces the RMST test (#188, thanks, @LittleBeannie).
• milestone() introduces the milestone test (#199, #204, #211, #237, thanks, @LittleBeannie).
• sim_gs_n() provides an experimental implementation for fixed sample size group sequential design simulation, with unit tests upcoming (#195, #201, #208, #212, thanks, @LittleBeannie and @jdblischak).
• create_cut() allows users to create custom interim and final analyses cuttings based on their specific requirements (#201, #221, thanks, @jdblischak).
• create_test() enables users to create various testing approaches for interim and final analyses (#215, #221, thanks, @jdblischak).
• multitest() gives users the option to perform multiple tests on a simulated dataset (#215, thanks, @jdblischak). Note: This function is still experimental and may be improved in future releases, as it was created prior to the standardization of test functions in #227.
• Test outputs (logrank, weighted logrank, RMST, milestone, MaxCombo) are now unified as a list including method, parameter, estimate, se, z-value, and p-value (#227, thanks, @LittleBeannie).

• Fixed incorrect weights generated by early_zero() under stratified designs (#233, thanks, @LittleBeannie).

• Enhanced documentation for get_analysis_date() (#186, thanks, @LittleBeannie).

• Removed dependency on the bshazard package as it was archived by CRAN (#234, thanks, @nanxstats).

This release makes minor improvements on auxiliary code with side-effects.

• Remove the code that sets options() within vignette("modest-wlrt").
• Updated the code used for generating image assets. These scripts now write to tempdir() instead of the package directory.

This release introduces significant changes to the API, improves simulation performance substantially, and adds new features and documentation.

• Complete overhaul of the API. Function and argument names now use snake case for consistency and readability. See the function reference for the updated naming scheme. Detailed change history is available in the merged pull requests (thanks, @LittleBeannie, @lili-ling-msd, and @XintongLi2023).
• Dataset names updated to snake case (thanks, @nanxstats, #164).
• The base pipe operator is now used throughout the package. The magrittr pipe is no longer re-exported (thanks, @nanxstats, #146).

• Rewritten table backend for simtrial functions using data.table, achieving a 3x to 5x speedup compared to the previous implementation (thanks, @jdblischak, #111).
• sim_fixed_n() now utilizes the %dofuture% operator for parallelization, enhancing flexibility and reproducibility (thanks, @cmansch, #110).
• rpwexp() adopts the inverse CDF method for random number generation, with the naive methods now as internal functions (thanks, @jianxiaoyang, #15 and #174).
• sim_fixed_n() is optimized to skip Breslow's method in the absence of ties (thanks, @jdblischak, #130).
• The internal function for computing Z statistics in Fleming-Harrington weighted logrank tests is now named wlr_z_stat() (thanks, @elong0527, #105).

• early_zero_weight() is added as a weighting function for early data removal (thanks, @LittleBeannie, #123).
• get_analysis_date() is added to calculate interim/final analysis dates under various conditions (thanks, @LittleBeannie, #122).

• New vignette("workflow") providing an overview of data manipulations involved in TTE simulations (thanks, @keaven, #99).
• New vignette("parallel") demonstrating the parallelization workflow and coding best practices (thanks, @cmansch, #113 and #134).

• Added a hex sticker logo with a generative art design for the package (thanks, @keaven, #158).

GitHub release in February 2023.

This is the version that enables parallel computation in simfix().

GitHub release in May 2022.

This version supports the Biometrical Journal paper "A unified framework for weighted parametric group sequential design (WPGSD)" by Keaven M. Anderson, Zifang Guo, Jing Zhao, and Linda Z. Sun.

Internal development release in August 2020.

• Updated vignettes and website.
• Prepared for Regulatory/Industry training session in September.

Internal development release in February 2020.

• Added wMB() to compute Magirr-Burman weights.
• Added vignette to demonstrate working with different weighting schemes.
• Replaced Depends with Imports in DESCRIPTION.

Internal development release in November 2019.

• Incorporated new functions to simplify use (simfix(), simfix2simPWSurv(), pMaxCombo()).
• Removed hgraph() with intent to put it into a release of gsDesign.
• Limited to 2 essential vignettes.
• Added continuous integration/continuous deployment (YAML) and pkgdown for website generation.
• Limited dependencies to those that are essential; this removed some convenience functions not related to core package functionality.