StATS: Temporality of Causes (April 7, 2004).
One of the nine criteria that Sir Austin Bradford Hill offers to establish a cause and effect relationship is temporality. In order for A to cause B, A must precede B in time. That seems logical enough, but every once in a while, you find someone who ignores temporality.
The classic joke along these lines was a statistician who was studying fire department records and concluded that the more fire engines you sent to a fire, the more damage they caused.
When scientists were first establishing that smoking causes lung cancer, some people offered the counter argument that cancer causes smoking. It's a difficult argument to make, but it was put forth with perfect seriousness. We all know that smoking preceded cancer, usually by several decades of time. The argument was that there were genetic tendencies towards cancer and perhaps these same tendencies also were related to the tendency to become addicted to nicotine. It's pretty easy to demolish this argument, of course.
Victor Stenger highlights another example in an article in the March 2004 issue of Skeptical Briefs. There was a cute article in the 2001 year end issue of the British Medical Journal titled: "Beyond Science? Effects of remote, retroactive intercessory prayer on outcomes in patients with bloodstream infection: randomized controlled trial." ([Medline]). The author, Leonard Leibovici, found the records of 3,393 adult patients with bloodstream infection at Rabin Medical Center, randomly divided those records into two groups then randomly selected one group to pray over. Note that this is a RETROSPECTIVE study. The outcomes were determined 4 to 10 years prior to the start of the study. After praying over one group, the author evaluated mortality, stay in the hospital, and duration of fever. Although there was no statistically significant difference in mortality (p=0.40), there was a reduction in the length of stay (p=0.01) and in duration of fever (p=0.04).
It is dangerous to speculate on the motives of the author, but this article was published in a year end issue that is traditionally reserved for light hearted articles.
Brian Olshansky and Larry Dossey treated the paper with quite a bit more seriousness, and in an article in the December 20, 2003 issue of BMJ argue for various physical mechanisms that could explain this result. They first argue that our understanding of how the world truly works is incomplete. For example, there is a classic result in physics where particles separated by vast distances of space can influence one another. There is no good explanation for how this occurs, therefore we shouldn't be too upset if there is no good explanation for how retrospective prayer would work.
They then cite obscure theoretical models in physics (bosonic string quantum mechanics and Calabi-Yau space) and research at the Institute of Transpersonal Psychology and the William James Center for Consciousness Studies that show retroactive influences in 10 out of a series of 19 experiments.
In my opinion, Olshansky and Dossey are making much too big a fuss about an article that was not intended to be serious research. This article was published in the same spirit as the Canadian Medical Association article, Celestial Determinants of Success in Research ([Medline]), that demonstrated an association between certain Zodiac signs and the likelihood of having received the Nobel Prize in Medicine and Physiology. Rather than demonstrating the validity of Astrology, this article was intended to illustrate that
foraging through databases, using contrived study designs in the absence of biological mechanistic data, sometimes yields spurious results.
The Leibovici article was clearly an effort to show the limitations of research methods by an example where a randomized controlled trial (RCT) shows a result that is truly bizarre. The results of this study should force us to confront the weaknesses of the RCT rather than the limitations of bosonic string quantum mechanics.
Furthermore, Olshansky and Dossey ignore a far simpler explanation of the unusual results: fraud. I have no reason to believe that Leonard Leibovici would manufacture these findings for personal gain, but quite frankly, the field of paranormal research, as a whole, has a quite troubling reputation for fraudulent claims. For that matter, the field of medicine has a quite troubling reputation for fraudulent claims. I recently received a recommendation for a book, Betrayers of the Truth by William Broad and Nicholas Wade that highlights that research fraud is a pervasive problem.
The best protection against fraud, of course, is replication by an independent group. This replication has not been done, perhaps because most people recognized that the Leibovici article was not intended to be serious research.
Olshansky and Dossey call on all of us to be open minded about the possibility of retrospective effects of prayer. But if they are willing to abandon commonly accepted principles about the temporality of causes and effects, without first asking for independent replication of this unusual result, perhaps they themselves are being a bit too open minded.
Some additional comments about the retrospective prayer article are worth noting. In the Rapid Response e-letters section of BMJ, Martin Bland raised the ethical issue of treating the control group.
According to Clause 30 of the latest revision of the Declaration of Helsinki: At the conclusion of the study, every patient entered into the study should be assured of access to the best proven prophylactic, diagnostic and therapeutic methods identified by the study. To meet this ethical standard, the prayer should now be said for the control group. If the treatment is effective, this should have the effect of removing the difference between the groups. I await the results with interest.
In separate e-letters, Eugenio Pucci and Christopher Price raise a different issue: informed consent. The author did not ask consent from the patients before conducting this experiment. Consent is often waived in retrospective studies because the research would otherwise be impractical. Surprisingly, informed consent has been waived for most PROSPECTIVE studies of prayer, where consent is actually quite easy to obtain. The rationale for waiving informed consent was to avoid volunteer bias, and perhaps this was also tempered by the belief that most people would not be offended at the thought of prayers being offered on their behalf.
As another aside, I was involved with a similar study (prospective, not retrospective). We planned this study using a one-sided hypothesis (remote prayer has a positive effect on health). The Institutional Review Board suggested changing this to a two-sided hypothesis (remote prayer has either a positive or a negative effect on health). Thankfully, we did not observe an outcome in the opposite tail as that would have been very difficult to explain.
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