Categorical nonsense, p<.05.

E fficient conversation has no place at lunch. On the surface, the Denise Kouri–Steven Lewis lunch of April 7, 2010, was pure muda (wasted time): too many topics, utter disorganization, innumerable tangents. Should we expect the young to memorize the multiplication tables? What percentage of the population has a passable grasp of statistics and calculus? (I didn't say we were fascinating, just inefficient.) This reminded D.K. that her daughter was reading a book on how research and scholarly publication have become tyrannized by a rigid notion of statistical significance – the .05 p value. If a phenomenon has less than one in 20 odds of occurring by chance, it's significant; if one in 19, it isn't. Rigour demands it, case closed. It popped into S.L.'s head that the same categorical logic governs medicare coverage: services are either in or out, " medically necessary " or dispensable options. When money is tight, look for a province or two to search for healthcare services to delist. Maybe it's tattoo removal or sex change therapy; maybe it's chiropractic treatments or optometric visits. Oregon famously ranked 800 or so services in order of priority and drew a cutoff line where the money ran out. The goal is a clear choice: the service is either in or out. (It must be noted that the experiment, like so many, had mainly middle-class people ranking services to be delivered to the poor. That didn't make it stupid or evil; it just meant that those preparing the Kool-Aid weren't bound to drink it.) It is important to understand the likelihood of a statistical finding occurring by chance, and likewise laudable to examine the usefulness of healthcare services. The error in both instances is making too much of minor differences and arbitrarily assigning nearly identical phenomena to different categories. Sometimes, as research grant review panels know only too well, arbitrari-ness is unavoidable. An application rated at 3.93 gets $400,000, and the next in line, rated 3.91, gets squat. Everyone knows this is conceptually absurd. When the National Institutes of Health in the United States sent out a batch of applications for a second round of review, about 20% of applications changed categories, from funded to unfunded and vice-versa. A score might have changed by a critical tenth of a point if reviewed by another committee, or three hours later in the day, or if one of the primary reviewers …