The most important reason for the extraordinary advances in medicine, agriculture, and other fields is the acceptance by practitioners of evidence as the basis for practice. In particular, it is the randomized clinical trial—more than any single medical breakthrough—that has transformed medicine (Doll, 1998). In a randomized clinical trial, patients are assigned at random to receive one treatment or another, such as a drug or a placebo. Because of random assignment, it can be assumed with an adequate number of subjects that any differences seen in outcomes are due to the treatment, not to any extraneous factors. Replicated experiments of this kind can establish beyond any reasonable doubt the effectiveness (or lack thereof) of treatments intended for applied use (see Boruch, 1997).