to simulate data from the specified distributions. A function to calculate weighted log-rank tests for the comparison of two
hazard functions is included. Also, a function to calculate a test using the maximum of a set of test statistics from weighted
log-rank tests (MaxCombo test) is provided. This test utilizes the asymptotic multivariate normal joint distribution of the
separate test statistics. The correlation is estimated from the data. These methods are described in Ristl et al. (2021)
Finally, a function is provided for the estimation and inferential statistics of various parameters that quantify the difference
between two survival curves. Eligible parameters are differences in survival probabilities, log survival probabilities,
complementary log log (cloglog) transformed survival probabilities, quantiles of the survival functions, log transformed quantiles,
restricted mean survival times, as well as an average hazard ratio, the Cox model score statistic (logrank statistic), and the
Cox-model hazard ratio. Adjustments for multiple testing and simultaneous confidence intervals are calculated using a multivariate
normal approximation to the set of selected parameters.
Imports: stats, graphics, mvtnorm, ggplot2, muhaz, survival, multcomp

Title: Sample Size Calculation under Non-Proportional Hazards
Description: Performs combination tests and sample size calculation for
fixed design with survival endpoints using combination tests under either
proportional hazards or non-proportional hazards. The combination tests
include maximum weighted log-rank test and projection test. The sample
size calculation procedure is very flexible, allowing for user-defined
hazard ratio function and considering various trial conditions like
staggered entry, drop-out etc. Trial simulation function is also provided
to facilitate the empirical power calculation. The references for
projection test and maximum weighted logrank test include Brendel et al. (2014)
references for sample size calculation under proportional hazard include
The references for calculation under non-proportional hazards include
Lakatos (1988) <doi:10.2307/2531910> and Cheng and He (2021) (under review).
Imports: survival, stats, mvtnorm, MASS, zoo
Author: Huan Cheng [aut, cre] (<https://orcid.org/0000-0002-2552-7656>)