Moneyball Medicine

Though the p-value "determines everything we do in  drug development or medical research," says Dr. Ulo Palm , it may be one of the most misunderstood and misused quantities in experimental science—drug discovery included. At its core, the p-value shows the probability that an observed effect was due to random chance. In other words, if a drug seems to outperforms a placebo with an associated p-value of 0.05, there's only a 5 percent chance that the study was wrong and that the drug is, in fact, no better than the placebo. A p-value of 0.05 is the accepted threshold for validity in most scientific research, even though it's an arbitrary standard set nearly a century ago by statistician Sir Ronald Fisher. "People don't often realize that this p-value of 5 percent was pulled out of thin air," Dr. Palm says. "If Sir Ronald Fisher had had six fingers, we would all be using a p-value of 6 percent."The issue, Palm says, is that an arbitrary dividing line of 0.05 leads journal publishers (and paper authors themselve