Harris and coauthors1 arranged for prayers to be said for patients in the cardiac care unit who had even medical record numbers; they found borderline significant advantages for this group in one measure of patient scores. Unfortunately, they failed to realize that investigators of seemingly paranormal effects must consider a much wider range of possibilities than those that occur in ordinary scientific work.
Waterhouse WC. Is It Prayer, or Is It Parity?. Arch Intern Med. 2000;160(12):1875. doi: