nph - Planning and Analysing Survival Studies under Non-Proportional
Hazards
Piecewise constant hazard functions are used to flexibly
model survival distributions with non-proportional hazards and
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) <doi:10.1002/pst.2062>. 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.
