StATS: More on the retroactive prayer study (June 10, 2005)
I discuss an interesting study on the effects of prayer (Leibovici 2001) published in BMJ, where the researcher prayed over a set of charts that represented outcomes occurring four to ten years earlier. When these results were compared to a control group of charts that were unprayed for, there was a statistically significant difference between the two groups.
This study flies in the face of what we know about causation (causes always precede effects), and another article in BMJ (Olshansky 2003) tries to develop a plausible mechanism for retrospective causation.
It's an interesting study that I discuss in a counterpoint to biological plausibility in my book on Statistical Evidence. A couple of recently published articles in the same journal also comment on this study, but I cannot access these articles easily because BMJ now limits access to some of their content for 12 months. When the 12 month window has expired, I may comment on these articles further.
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