Love is blind. Of course it is. Still, there’s no reason to believe that there aren’t legitimate, data-driven ways to improve your dating life. So I recently joined up with Christian Rudder of OkCupid, a matchmaking site that takes a playful attitude toward the data it collects (like which camera takes the most successful profile photos). I asked Rudder if there was a way to determine which days of the week — and which times of day — are the best to meet someone at a bar. What he came up with is something called the “sexual availability index.”

“It’s not unlike the Dow,” he said, “if the stock market were about sex.”

Rudder started by finding out, based on OkCupid’s mobile service, which customers in New York, Boston and Washington were out on the town on a given night. From these people’s profile data, Rudder then built a composite of four sets of personal characteristics that might correlate with openness toward new (but not necessarily long-lasting) relationships.

Two measures he studied were explicitly concerned with sex: what percentage of singles out on a given evening listed casual sex as a “romantic priority” and what percentage was willing to sleep with someone on a first date. The other two measures were less sex-centric: what percentage described themselves as extroverted and what percentage fancied themselves as adventurous.

When he put all the numbers together, he got a curious result. Weekdays, not weekends, are better for singles on the prowl — and the mix of people out on Wednesday nights are the friskiest. (The least surprising bit of data is that someone’s chances of success increase over the course of an evening.)