WHICH-50 - Apr 9 - eHarmony is using machine learning and data science to figure out its users' preferences to make more successful matches. eHarmony uses two techniques to match singles. The initial match is based on compatibility. This measure is determined by the extensive questionnaire. eHarmony then uses machine learning, which it calls affinity matching, to learn about behaviour on the site as an indicator of what users like. The site currently runs 20 different affinity models.