topic Re: Calculating required number of events and time to required number of events in Statistical Procedures

Calculating required number of events and time to required number of events

sensass5224950 — Mon, 20 Oct 2025 18:03:12 GMT

I am planning a two arm double-blind study with ratio (1:1) and am planning sample sizes. I need to calculate the required number of events and the time to reach the required number of events based on a survival function for an exponential model assuming constant hazards.

I have EFS rates and hazard ratios as well as drop out rate and alpha which I think the program needs to incorporate. Can someone please help with a SAS program to determine these values?

Re: Calculating required number of events and time to required number of events

sbxkoenk — Mon, 20 Oct 2025 19:03:15 GMT

Hello ,

This SAS Global Forum 2020 paper may help:

Paper 4908-2020

Surviving the Cox Proportional Hazards Model with the POWER Procedure

Rachel R. Baxter, Grand Valley State University and Spectrum Health Office of Research and Education

https://support.sas.com/resources/papers/proceedings20/4908-2020.pdf

Note that :

for a fixed-sample design, you should use the POWER and GLMPOWER procedures to compute sample sizes.
for a Group Sequential Design, you should use the SEQDESIGN procedure.

Ciao,
Koen