Avid Bioservices Inc (CDMO)

[exwannabe]

You explained stat sig well but something needs to be added. The p < 0.05 is really arbitrarily set number, it is 5% or second standard deviation. What that means is that if a drug is approved with p=0.04999 the chance is still about 5% that the drugs really doesn't work and the result of that particular phase 3 was a statistical fluke. We could have set the standard for approval to be first standard deviation, or the third one, or any number in between. So saying that p=0.04999 is stat sig and p=0.05001 is not and sticking strictly to that as a condition for a drug approval is almost ridiculous.

I certainly agree that .05 is an arbitrary number.

But P value does not imply the probability that the drug does not work. It is the probability that a placebo could have duplicated the results.

Thought experiment:

Grab a random stranger in the US and ask them to flip a coin 5 times. If it comes up heads all time, would you really think it is probably 2 headed, or would you think it is luck?

Repeat the same experiment on Mars, would you be more likley to suspect the coin had 2 heads?

The chance that the drug works or not is a Baysian number, and the FDA stat boys are frequentists so will not even discuss this.