Just a couple of general thoughts on this.
Firstly it seems to me that trying to compile statistics on prayer makes a mockery of the whole idea of prayer. A prayer can't be just about saying or thinking the words and then waiting to see what the result is. It isn’t just a magic formula to get what we want.
Secondly I don’t agree that everything that can’t be confirmed scientifically is just simply faith. Not all evidence is scientific. The Bible is evidence that isn’t scientific. The fact that there is something rather than nothing is evidence that isn’t scientific. Our moral code is evidence that isn’t scientific.
With wisdom, we then apply reason to all that we know and come to our own conclusions. Actually the fact that I can come to one conclusion and Crashfrog to another is in my view evidence in itself.
At some point in time though being a Christian does require a leap of faith, but in my view that leap of faith is reasonable but not scientific. I have read Collin’s book “The Language of God” and that is certainly the approach that he has taken. His science is part of the evidence to which he has applied his reason to come to the conclusions that he has.
Everybody is entitled to my opinion.