Then come the explanations (from believers of faith-based healing) for why a measurable effect was not observed: there was too much “noise”, i.e. too many prayers already being said for everyone, such that the effect of extra prayers couldn’t be measured. Another excuse: the prayers were not said loud enough, or close enough, or the “energy” wasn’t “channeled” properly. The list goes on and on. And because you can never prove the null hypothesis - you can never prove there isn’t an effect - people continue to attempt to show a relationship. No doubt, by chance alone, there will someday be a study that finds such an effect - bias aside. That’s because statistics has a built-in possibility for error.
Here is another one of those variables for you; Did God even hear the prayer?
Sounds like a silly question, but it all depends on what type of God you believe in.
(Above copied from Stats.org)