Experimental prayer study

Many religious people say a prayer to their god or goddess when under stress. It is not clear by what mechanism or what causal link prayers might reduce the cause of that stress and the effectiveness of prayers for eliminating stress is in doubt. David Spiegelhalter, as statistician, reports: "There have even been studies to determine the effectiveness of prayer. For example, the Study of the Therapeutic Effects of Intercessory Prayer (STEP) randomly allocated over 1,800 cardiac bypass patients into three groups: patients in Groups 1 and 2 were prayed for and not prayed for, respectively, but did not know which was the case, while Group 3 knew they were being prayed for. The only apparent effect was a small increase in complications in the group that knew they were being prayed for: one of the researchers commented, ‘It may have made them uncertain, wondering, “Am I so sick they had to call in their prayer team?”.’

Spiegelhalter, David. The Art of Statistics (Pelican Books) (S.107). Penguin Books Ltd. Kindle-Version.