Replies to post #138551 on Biotech Values

[iwfal]

ONTY

What I don't understand is how you derived "final alpha" vs the nominal alpha of .05

There are "sample size" formulas for determining the size a no-interim trial needs to be to in order to have the desired power. I.e.

Number of Events=F(Alpha, presumed HR, enrollment ratio, desired power).

I just inverted the formula to find alpha given the number of events.