The program uses the following formula for the total sample size
Where fi is the proportion of the sample in treatment i and ei are the event probabilities in treatment i, q is the inverse normal function and
Where HR(exp./std.) is the hazard ratio between the experimental and standard treatments and HREquiv(exp./std.) is the hazard ratio defining equivalence.
The user is prompted for values to the following items. For items that have initial default values set, the values are given in parentheses.