We define risk, using dictionary terms, as "the possibility of loss or injury." Academics, however, like to define "risk" differently, averring that it is the relative volatility of a tock or a portfolio of stocks that is, the volatility as compared to that of a large universe of stocks. Employing databases and statistical skills, these academics compute with precision the "beta" of a stock its relative volatility in the past and then build arcane investn1ent and capital allocation theories around this calculation. In their hunger for a single statistic
to measure risk, however, they forget a fundamental p1inciple: it is better to be approximately right than precisely wrong.