Biotech Values

[iwfal]

DNDN -

What I get though is an alpha of .060. The difference is more than can be accounted for by rounding. As an additional check prior to the SPA amendment the protocol called for 360 events, 90% power, overall alpha .05, and HR 1.45 (1/.6897). When I run that through the formula I get alpha .041 (note Pocock boundary, interim at 50% info fraction).

I.e. are you saying they were disingenuous when they amended the SPA? Hush now. How could that be? -g-

I publicly noted from day 1 that the power they were claiming after the change in SPA was extreme spin - I hadn't done the particular calculation you just did, but had done more sophisticated calculations (modeling) and it was clear they were not being forthright. Also note that prior to the SPA change they were clear that the HR assumed for powering calcs was 1.45 - but I don't believe they ever quoted an HR associated with the post-SPA powering.

As for the check that the pre-change numbers were realistic - I had not done that calc before. So that was interesting in an of itself. Tx

Historical note for those who weren't following DNDN at the time. They amended the SPA mid-trial to reduce total events from 360 to 304 (and changed interim point and alpha) and claimed it reduced powering from 90% to 88%. It was dead obvious at the time that they were either idiots or being disingenuous to claim only a 2% reduction in power. But it was also controversial with a variety of defenders who should have known better claiming the company must be right.