Zuckerberg said that in 2013 researcher Aleksandr Kogan from Cambridge University had created a personality quiz app, which was installed by 300,000 people. The app was then able to retrieve Facebook information, including that of the users' friends, and this was obtained by Kogan. It was not until 2015 that Zuckerberg learned that these users' information was shared by Kogan with Cambridge Analytica.