The site also publishes OkTrends, a blog about data it collects. If mathematicians wrote an advice column on how to get a date, it would look like this. The site’s users can learn from the stats to build a better online profile. For example, it’s best not to smile in pictures: women who made a ‘flirty face’ with eye contact received more messages, while men should sport a serious expression and look away.
Yagan says, “Think about shopping: nobody is an online or offline shopper. It’s the same with dating: you shouldn’t be an online dater or an offline dater, you should be both.”
Is there a formula for calculating compatibility and finding love online? JV Chamary finds out whether meeting your perfect partner is a problem that can be solved with an algorithm
Our busy modern lives make it hard to meet new people, so more and more of us are turning to technology to find that special someone. Once the last resort for lonely hearts, online dating has become socially acceptable, even widespread – 4.7 million British people visited a dating site during 2008.
But popular as such sites may be, finding your ideal match online can take a lot of time, as traditional dating sites force users to read dozens or even hundreds of profiles. So some sites are helping people narrow the field by using an algorithm – a set of logical instructions for solving a problem – to find love online.
These algorithms take personal information, such as your interests, and push the data through a computer to calculate a couple’s degree of compatibility (or lack of).
Services like GenePartner offer DNA tests to check for genetic compatibility, while OkCupid’s matching algorithm is powered by a user-generated personality test. eHarmony, the second-biggest dating site, carries out scientific studies to improve its algorithms.
PSYCHOLOGY: Matching personalities for long-lasting relationships
Unlike traditional sites, they don’t let people browse a database. Instead, members take a personality test upon signing up with the service, and their answers are entered into a matching algorithm to calculate compatibility with potential partners.
eHarmony has a reported 33 million members worldwide and even has its own lab, where psychologists question and observe couples and use the results to continuously refine the matching algorithm. “We see which parts of the compatibility model are the strongest, and how we can revise the model to make better matches,” says Dr Gian Gonzaga, director of research and development at eHarmony Labs in Santa Monica, California.
eHarmony was founded in 2000 by Dr Neil Clark Warren, a clinical psychologist and marriage counsellor who, after spending over 35 years trying to stop people from getting divorced, realised that the best way to build long-lasting relationships was 
to make sure people were compatible to begin with.
His researchers came to the conclusion that a person’s key character traits and values are the factors that best predict future relationship success.
Using this information, they created a personality test that was taken by thousands of married couples, who also completed a test to measure their relationship satisfaction. By cross-referencing the responses from these two questionnaires, Warren worked out which characteristics two people would need to have in common, in order for them to be compatible. Applied to single people, this became eHarmony’s first matching algorithm.
Online matchmaking services like eHarmony and Chemistry are designed for those who are serious about dating
Today, the personality questionnaire has about 300 questions (the original research used 700), but the algorithm is much more complicated. If two people get 90 per cent compatibility, for instance, it doesn’t mean they answered nine out of 10 questions the same – whether you’re an extrovert or an introvert carries more weight than your shared hobbies, for example. The result is a shortlist of compatible people, and users are shown four or five profiles every day.
