koegen to harvest data for them through a facebook personality quiz. >> we collected a very specific type of data so we collected people's demographic details. like their birthday, their location, their gender and then we collected and then we collected page likes. >> what some failed to understand from the fine print was the app also took their friends information. >> the average person at that point i think had about 300 friends. so we collected the user and the 300 friends. so from just the 200,000 times 300 you get 60 million. >> taking redundant user profiles in account he estimated he obtained data from a staggering 30 million people which he shared with cambridge analytica. the massive information grab might never have been public knowledge had it not been for