Interaction Survival is a program to calculate either estimates of sample size or power for tests of interaction.
Exponential distributions are assumed and are specified as a ratio of the hazard ratio for the treatment effect in stratum 1 to the hazard
ratio for the treatment effect in stratum 2.
The program allows for unequal sample size allocation in the four cells defined by the two treatment groups and two strata.
An exponentially distributed competing risk is also permitted.
For further details, view the