CIO.COM - Mar 21 - Dating site's tech chief Prateek Jain shares the machine learning secrets of eHarmony. When a user signs up to eHarmony they fill out a lengthy questionnaire about the type of person they are, their likes and dislikes, beliefs, values and preferences in potential partners. The information is fed into the company's closely guarded, secret algorithm, which serves up the most compatible matches in its user base. The matching algorithm is based on data collected from interview with ~50k married couples in 23 different countries. The result is the ultimate recommendations service for singles. "We say we're like Netflix," Jain explains, "but the movie has to like you back." Matches are based on far more than just the questionnaire; such as how users behave on the site, the profiles they click on and the content of their self-descriptions. "All these indirect signals we look for, it allows us to refine the filter," Jain says. Using Google's Cloud Vision API, user profile pictures are scanned for a number of features – including hair and eye colour, whether the image shows a beard or moustache as well as 'has cleavage' and 'deduced BMI'. A user that more frequently clicks on blonde-haired user profiles will be served up with more blonde matches. Occasionally, the site will serve up a match that is outside user's usual preferences, called 'Serendipitous Recommendations'. This helps users from 'getting caught in a bubble', Jain says.