I_luv_cydy,

Normaly the binomial distribution is used to make the calculations in the case of S-C as the outcome is either the patient survives or doesn't:

Quote:

---

The binomial distribution model allows us to compute the probability of observing a specified number of "successes" when the process is repeated a specific number of times (e.g., in a set of patients) and the outcome for a given patient is either a success or a failure.

---

As we have two groups this is sometimes called a two group independent test. Some information below:

https://www.statsdirect.com/help/proportions/unpaired.htm

A more formal approach is here with info in the p-number:

https://ncss-wpengine.netdna-ssl.com/wp-conte...rtions.pdf

You can build your model (in excel for example), or use a statistical package (like S.A.S.). There are websites that do the calculations, I take it you want to understand where the number comes from

Let's hope today we continue in an upswing so we can celebrate 4th July in style.