Quote: "Of these nine classic characteristics, we can imagine people scoring either “nerdy” or “anti-nerdy” on each. If that were true, there’s only a 1/2^9 = 1/512 chance that any given person has all of these characteristics."<p>Not if the traits are correlated with each other. The chosen binary math treatment works only if the traits are independent, i.e. mutually orthogonal. They aren't -- nerdy traits are strongly correlated, so much so that if you find any five of the nine traits in an individual, you're most likely already done identifying a nerd.<p>Also, there's a more efficient way to express a fractional probability: 1/a^b = a^-b.