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But with 70% reduction in deaths, would that very probably have resulted in a great p value and a recommended halt in the trial??

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Calstang,

Yes, 70% reduction, or 50% reduction probably will lead to trial stoppage. However this depends as well on the POWER of the sample (number of patients). FDA requires this to be 80%-90%.

It is quite possible that we had a good p-value at interim but the power was not still there. That is precisely why the fact that the are taking a new look at 75% can be construed as positive: the statistician thinks that we can achieve both, a low p-value and high-enough power at this time.