P.Mean >> Category >> Corroborating evidence (created 2007-06-18).

Corroborating evidence is information from outside the research study that supplements and strengthens the persuasiveness of a research finding. Articles are arranged by date with the most recent entries at the top. Also see Category: Conflict of interest, or Category: Fraud in research. You can find outside resources at the bottom of this page.


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Creative Commons License All of the material above this paragraph is licensed under a Creative Commons Attribution 3.0 United States License. This page was written by Steve Simon and was last modified on 2010-04-11. The material below this paragraph links to my old website, StATS. Although I wrote all of the material listed below, my ex-employer, Children's Mercy Hospital, has claimed copyright ownership of this material. The brief excerpts shown here are included under the fair use provisions of U.S. Copyright laws.


10. Stats: A nonspecific diagnostic test (October 13, 2005). Someone posted a note on the IRBFORUM complaining that the IRB was preventing him/her from volunteering for a test. This company has a very promising "non-intrusive Universal Early Cancer Detection test" but the company could not take any volunteers before getting IRB approval. There were a lot of good comments, but one thing that caught my eye in a later email was the following claim: Besides, the test itself is non-intrusive: they will take 2 micro liter samples of blood and within 3 hours we get our results on any type of 1_week_or_older cancer. This claims illustrates a very important point: research claims which lack specificity also lack credibility. A treatment that claims to cure everything probably cures nothing.

9. 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.


8. Stats: Prayer studies (December 13, 2004). I've been meaning to write a web page about the series of studies that seem to indicate that groups of patients receiving prayer get better health outcomes than the control group. It is an interesting series of studies because it illustrates some of the difficulties, even with randomized double blind trials.

7. Stats: Research on therapies that have no known mechanism of action (November 4, 2004). Several people on the IRBForum have made comments along the lines that research on certain alternative medicines (such as homeopathy) has no scientific merit because there is no known mechanism by which these therapies can work. Since there is no scientific merit, there is no balance between the risks and benefits. This leads directly to a conclusion that it is unethical to conduct a study on these alternative therapies.

6. Stats: Is there a mechanism? (July 23, 2004). "Extraordinary claims require extraordinary proof." This is the mantra of skeptical thinkers and it provides useful for evaluating claims that fall outside the mainstream of science. This is part of the network of corroborating evidence that we demand as we review research claims in medical journal articles. One aspect of a claim that makes it extraordinary is that there is no plausible mechanism that would explain how the therapy works. Therapies without such a mechanism would be subjected to a higher standard of proof. Don't reject a therapy automatically, though, just because no known mechanism exists. Many successful medical interventions were adopted before a mechanism was discovered that explained how and why that intervention worked.

5. Stats: Small relative risk (June 30, 2004). Someone asked me about small relative risk. It was only 1.12, but because of the large sample size, it was still statistically significant. This person wanted to discount the relative risk because anything less than 2 is unreliable. This is a point of controversy. I don't think that you should disregard a relative risk less than 2.0, but I do think you need to hold it to a higher level of scrutiny.

4. Stats: In vitro fertilization prayer study (June 29, 2004). High on my priority list is a page talking about the recent prayer studies. These are interesting studies because they highlight important issues about causation. I've already discussed a retrospective prayer study that highlights the importance of temporality. Issue #22 of the eSkeptic newsletter discusses apparent fraud in a different prayer study.

3. Stats: Health effects of smoking (May 31, 2004). A recent Surgeon's General report on smoking adds new cause-and-effect links between smoking and several diseases including cataracts, pneumonia, acute myeloid leukemia, abdominal aortic aneurysm, stomach cancer, pancreatic cancer, cervical cancer, kidney cancer, and periodontitis. Drawing a cause-and-effect link requires great care.

2. 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.


1. Stats: Causation (January 27, 2000). Dear Professor Mean: Everyone says that smoking causes cancer, but we can't really say that, can we? There is an association between smoking and cancer, but we know that association does not imply causation, don't we?

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Creative Commons License This work is licensed under a Creative Commons Attribution 3.0 United States License. This page was written by Steve Simon and was last modified on 2010-04-11.