In his lengthy response in the last issue of Research News, Dr. Weaver commendably admits my central point, which is that the reports of a positive connection between religious behavior and health are not sufficiently significant to draw the frequently heard conclusion that the existence of the supernatural has empirical support. As he puts it, "Even if there is a beneficial relationship between religion and health, one cannot therefore prove from those findings that there is a God or Divine involvement in events.
Unfortunately, this is not the way the bulk of the studies that Dr. Weaver cites are perceived by the public. Many of the authors of these reports appear on TV, are interviewed by other media and write popular books in which they make claims that far exceed the significance of their results.

 
Even if nothing supernatural is being claimed, the implication that significant health benefits result specifically from religious behavior is not supported by the evidence. As I mentioned in my original essay, and as pointed out by Sloan and others, epidemiological studies are extremely difficult to analyze because of confounding factors. Thus, if it is found that churchgoers are healthier than those who stay home on Sunday morning, one must allow for those who are too ill to get out of bed. I mentioned one such paper that was withdrawn after it was found that the immobility of the ill was not taken into account.

 
In most cases, the published studies have been reported in medical journals. Unfortunately, the publication standards of medical journals are quite low compared to other science fields such as physics, which makes them inappropriate venues for extraordinary claims. The low standard is presumably necessary to assure that possible helpful therapies are not kept from needy patients for too long. In many cases their efficacy, is far from proven and quote studies commonly disputed by later studies.

 
Unlike physicians, however, physicists and other non-medical scientists are not in the business of saving lives but rather that of investigating extraordinary phenomena. Those who claim efficacy for therapies that go beyond established medical science should be bound by the stricter standards of those fields that deal with extraordinary claims. I am not asking that they be held to a higher standard, just the same standard that my colleagues and I were required to meet in 1998 when we published the claim that the neutrino has mass.

 
Scientific journals require a minimum standard of statistical significance for the publication of a claimed empirical effect. The “probability level” quoted in many scientific papers is what statisticians call the “p-value.” For example, suppose an effect is reported with a p-value of 0.05, the typical threshold of medical journals.

 
Technically, this means that in a long sequence of identical experiments we would expect to observe an effect as great or greater produced by statistical fluctuations in five percent of the cases. This not the same as the “likelihood” or “probability” that the results were due to chance, although authors often wrongly state it in this way. In fact, it is always possible to get any observed effect by chance. You simply have to repeat the experiment enough times.

 
To illustrate this point, let me use as an example one of the highly publicized experiments involving remote intercessory prayer. In these studies at least the investigators can attempt to control for confounding factors in a way not possible in epidemiological studies.

 
Cardiologist Randolph Byrd has claimed that coronary patients benefit from blind, distant intercessory prayer. But his p-value is only 0.05, apparently sufficient for publication in the regional Southern Medical Journal. However, Byrd’s observations would be expected from statistical fluctuations on average every twenty experiments. And, since null results are rarely reported, one can easily imagine 19 other unpublished experiments showing no effect with their data sitting in file drawers.

 
Another study along the same line as Byrd’s has been published in a major international medical journal, Archives of Internal Medicine, with nine co-authors. There, positive results are reported at a p-value 0.04, but for different criteria than Byrd’s. In fact, they fail to confirm Byrd’s specific results.

 
No respectable physics journal would publish a result with a p-value of a few percents. If it did, many papers would contain false claims that were only statistical artifacts, wreaking havoc with the whole research enterprise. In fact, the publication standard in physics is typically a p-value of 0.0001, that is, only one in 10,000 similar experiments would be expected to produce the reported effect or a greater one as a statistical fluctuation.

 
This was the case for our discovery of neutrino mass and all of the other great discoveries in physics over the past 50 years. Furthermore, I can cite from experience many investigations that reported effects at levels of significance far higher than any of these religious studies that failed to be confirmed by independent experiments.

 
To simply say that many studies have appeared in peer-reviewed journals does not imply that they have demonstrated anything extraordinary that cannot be explained by known material processes. I am sure going to church lowers your blood pressure for an hour or so. The experiments referred to by Dr. Weaver have been seriously misinterpreted by those who seek scientific confirmation for their religious beliefs. If anything, the lack of significance of such a huge body of work can be taken as empirical evidence for the absence of a supernatural power that plays an active role in human affairs.

 

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Victor J. Stenger is professor emeritus of physics at the University of Hawaii and visiting fellow in philosophy at the University of Colorado.