The Epidemiology of Small Effects

Abstract

Epidemiology faces significant challenges when dealing with suspected risk factors whose effect is likely to be small. In such cases it is particularly important that epidemiologists carefully consider problems that may be associated with case-control selection, biases, confounders, subgroup analysis, and interactions. As we examine, for instance, the possible effect of cellular telephones on brain cancer general symptomology that may be claimed to be associated with such use, it is vital that all of the problem areas are carefully considered before drawing a conclusion as to causation. However, if these various problematic areas have been carefully considered and to the extent possible, if they have been avoided, then a conclusion as to causation can be made, particularly if they meet the criteria in respect to Judgment as well delineated by Bradford Hill. When dealing with weak associations and proper conclusions, the science of epidemiology must be at its optimum.