Chris Coyne, Max Krohn, Sam Yagan, and Christian Rudder

Ruse Laboratories
Mar 18, 2015 2:49AM


They write: 

“We met at Harvard during the late 1990s, in the first blush of the dot com era. Using no school resources whatsoever [cough], the four of us authored and programmed, a site that published personality tests, quizzes, goofy science projects, and fabulously funny e-greetings and e-cards. In 1999, the team branched into higher academia with SparkNotes, a free competitor to Cliffs Notes written by Harvard students and alumni. Millions of kids have used SparkNotes to augment, or supplant, their learning. The SparkNotes brand has been proudly owned by Barnes & Noble since 2001.

We reunited in New York City in 2003 and began work on a website for dating, a milieu befitting our expertise in math and computer science. OkCupid went live in 2004 to modest fanfare and has grown steadily since, like a modern-day black plague, spreading by ship and horse to all corners of the globe. We remain great friends.”

About the OkCupid Compatibility Calculation

OkCupid’s compatibility calculation was invented in early 2003 and unleashed on the world in early 2004. Previously, popular dating sites employed "relationship experts" - psychologists, therapists, and statisticians who studied straight couples in vanilla by-the-book relationships. These subjects claimed, on surveys, to be happily married. Then, the subjects were mapped into N-dimensional space and patterns were found, yielding rules about how to measure love.

This reduction ignored the uniqueness of the individual. Not in a small way, but in a really deep, crucial way. Each person's passions, fringe tastes, hidden quirks, and lusts are perhaps the most important aspects of chemistry. Even what specifically went wrong in a last relationship might drive the desires of the next.

Before doing any math at all, OkCupid played a mental exercise. It imagined a trusted friend claiming they had the perfect match for you.  Would you even trust that person, your closest friend? Probably not — you’d start asking questions.  What questions would you ask about this perfect match?  How much would you care about each answer, and what would you hope for? If you could play this game long enough, asking and answering questions through your friend, you could form your own, custom opinion, and disregard your expert friend entirely.

This was OkCupid’s goal: to disregard the expert.  Instead, it simulated a personalized game of Q&A between all pairs of people in the world, all at the same time. Of course, everyone could answer different questions and it would still work. Some questions would be common (“Is there a god?”) and others would be unusual (“Would you like to dress up like a furry animal and cuddle with your match?”). The more anyone played with this game, the more they would be building their own, custom matching system, while answering others.  And anyone could introduce a question at any time. At no time would an expert's opinion or survey of another relationship ever affect a match calculation.

The answer ended up simple.  A match percentage on OkCupid is designed to reflect the odds you would like someone’s personality, given that you’re honest about your own tastes. OkCupid looks at the intersection of questions that 2 users (call them A and B) have answered, and then, for each question, figures out whether party A has satisfied party B, and how many points that is worth. Even the points are up to the user. Together, this yields a weighted score of satisfaction. This is combined symmetrically: A’s score of B and B’s score of A are multiplied together.  Finally, a confidence adjustment is made based on the size of the questions. The more A and B have asked of each other, the more confident they can be of their score.  

This confidence adjustment is the only part of the formula that has been tweaked in OkCupid’s history, and this artwork represents the original version, mostly unchanged. It is responsible for millions of relationships. If you know anyone who has had any kind of connection due to OkCupid, this formula was behind it.

- Chris Coyne, Max Krohn, Sam Yagan, Christian Rudder

Chris Coyne

Max Krohn

Sam Yagan

Christian Rudder

Ruse Laboratories