A Nice Null Result

OkCupid is a dating site that takes a pleasantly data- driven approach to the online dating game. If you read their blog, you run into a lot of interesting and surprising facts that the OkCupid staff have pulled out of their databases.

Like many dating sites, OkCupid gives its users a list of questions to answer about themselves. For each question, however, it also lets you specify what your ideal partner’s response would be, and how important that response is to you. (You might not always want your partner to have the same response as you — for instance, “Are you sexually dominant?”) This lets OkCupid rate the compatibility between two members according to their personal standards, not just according to what the employees at OkCupid think makes for a good couple.

You can then do interesting aggregate statistics by breaking the users down into groups and then looking at the average compatibility between different groups. On this post on the OkCupid blog, they did various breakdowns and visualized the results on grids like the one below. Each group has its own row and column, and the intersection of a row and column gives the average compatibility between the two groups. A greener color means above- average compatibility, and a redder color means below-average compatibility. For instance, here are the compatibilities of racial groups:

Dating compatibility between racial groups, taken from blog.okcupid.com
Dating compatibility between racial groups, taken from blog.okcupid.com

This is somewhat heartening: in theory, people of all races should be able to get along pretty well in relationships. (Unsurprisingly, in practice, this is untrue. Different racial pairings on OkCupid reply to each other’s messages at rates that vary wildly from what their compatibility scores would imply, indicating that people’s personal attitudes affect things strongly. See the blog post for more info.)

Anyway, here’s that null result that I referenced in the title:

Dating compatibility by zodiac sign, taken from blog.okcupid.com
Dating compatibility by zodiac sign, taken from blog.okcupid.com

From a sample of 500,000 users, 144 comparisons, all within 0.5% of the mean value. That’s a null hypothesis that I can get behind.

(As a side note, the fact that OkCupid lets people rate the personal importance of others’ answers to various questions allows them to easily discover which questions are the most effective for testing compatibility. Apparently “How often do you shower?” is one of the best.)