p3analyze........................
very nice work, you have the OBF stuff down too.
my only comment:
"2. However, if using the pooled hazard ratio of 1.5 from 9901 and 9902a, to power the study at 90% would require only 256 events, which means the final analysis can be done by end of Dec 2007, and data release in 2008.
3. A conservative powering approach would be to use HR observed in 9902a, ie 1.3, but that would require 456 deaths to have 80% power, therefor this senario is not likely."
I would guess then that the HR is not 1.3 , but closer to 1.5 - the target of 75% of events is the extreme end of the spectrum, and usually just past the median is reasonable for a survival trial.
I have seen them too set up this way: expect median survival on the control arm to be X months; at that point in time, what will be the relative event level in the drug arm ? If then S(t) = 0.4 (say) then you need only 55% of events.
So I expect the target HR is closer to 1.5, and you should figure on around 275 maybe 300 events at most.
(I know others have said 75% of events, and if they have convincing arguments to make for that, that would be great, and perhaps on this board we will arrive at where it should be !)
"....on the biotech battle-field, you need some élan...."
