I’m surprised the figure is that low.
From “False Positives in Cancer Epidemiology” in the Nov. 1 issue of Cancer Epidemiology, Biomarkers & Prevention:
The claims that the frequency of false positives in epidemiology is relatively low and that false negatives may pose a greater problem than false positives are without scientific basis. False-positive findings dominate the epidemiologic literature under the current standards of practice, with empirical evidence indicating that there are at least 20 false-positive results published for every true-positive finding. This is not surprising in view of the increasing number of epidemiology journals, articles, and the pronounced incentives on the part of researchers and journals to publish positive results. Thousands of potential risk factors have been investigated in the last 4 decades, yet the true known primary causes of the major cancers, save lung and cervical cancer, are extraordinarily limited. The potential for false positives is further increased by common practices in the analysis and interpretation of individual epidemiologic studies, including the use of multiple exposure metrics for a risk factor of interest, the fitting of multiple statistical models, the analysis of numerous subgroups, and the selective reporting of analytic results. It has been asserted, without benefit of any evidence, that false-negative findings occur about as often as false-positive findings in epidemiologic research. In fact, however, false positives occur much more often than false negatives in most epidemiologic study settings.