The first literary mystery to be solved by numbers was a 150-year-old whodunit finally put to rest in 1963. Two statistics professors learned of the long-running debate over a dozen contested essays from The Federalist Papers, and they saw that they might succeed where historians had failed. Both Alexander Hamilton and James Madison claimed to have written the same 12 essays, but who was right?
The answer lay in how each writer used hundreds of small words like but and what, which altogether formed a kind of literary fingerprint. The statisticians painstakingly cut up each essay and counted the words by hand—a process during which “a deep breath created a storm of confetti and a permanent enemy.” And by comparing hundreds of word frequencies, they came up with a clear answer after so many years of speculation: the contested essays were distinctly the work of James Madison.