One of their findings is that women are far more likely than men to use personal pronouns ("I", "you", "she", etc), whereas men prefer words that identify or determine nouns ("a", "the", "that") or that quantify them ("one", "two", "more"). According to Moshe Koppel, one of the authors of the project, this is because women are more comfortable thinking about people and relationships, whereas men prefer thinking about things. But the self-styled "stylometricians", in creating their gender-identifying algorithm, have been at pains to avoid the obvious.

Men and women ostensibly write the same language, on the other hand, but according to a recent article in The Boston Globe, they do so in ways that immediately reveal which sex is doing the writing. A team of Israeli scientists, the Globe article reports, punched into a computer some 600 published documents and devised an algorithm that could predict with 80 percent accuracy the sex of the author. …

When the Israeli stylometricians, as they call themselves, study a text, they scrub it clean of everything that's "topic specific" — in other words, no "gown," no "princess," no "keg," no "bullet-resistant." This is how sophisticated language analysts work these days. They ignore the obvious stuff and concentrate instead on the seemingly unobtrusive little tics that the writer and reader barely notice. The process is a little like identifying Tom Wolfe by ignoring his suits and his spats and concentrating instead on his socks, but it gets results. Seven years ago, for example, Donald Foster, the Vassar English professor and self-styled "forensic linguist," fingered Joe Klein as the author of "Primary Colors" from Klein's use of punctuation and adverbs.

An even more effective way of rebutting F.'s dating would be to show that the case can be made for another date on stylometric grounds. After all, statistics can never have a probative value. The basic logic of statistical investigation is to turn skepticism against itself: you cannot prove anything, you can only disprove a hypothesis. Thus, the statistician, or stylometrician, does not claim to have proved something like a date for the Ars Poetica in the period 24-20 B.C.; she simply disproves the probability that any other period of Horace's creative life falls more firmly within her confidence interval.