It has been widely reported that Facebook builds profile of people even if they have never signed up for its services. However, in a hearing with the House Energy & Commerce Committee on Wednesday, when New Mexico Representative Ben Lujan asked Facebook CEO Mark Zuckerberg if he was aware of the so-called practice of building "shadow profiles", Zuckerberg denied knowledge of it. Here's the exchange: Lujan: Facebook has detailed profiles on people who have never signed up for Facebook, yes or no? Zuckerberg: Congressman, in general we collect data on people who have not signed up for Facebook for security purposes to prevent the kind of scraping you were just referring to [reverse searches based on public info like phone numbers]. Lujan: So these are called shadow profiles, is that what they've been referred to by some? Zuckerberg: Congressman, I'm not, I'm not familiar with that. Lujan: I'll refer to them as shadow profiles for today's hearing. On average, how many data points does Facebook have on each Facebook user? Zuckerberg: I do not know off the top of my head. Lujan: Do you know how many points of data Facebook has on the average non-Facebook user? Zuckerberg: Congressman, I do not know off the top of my head but I can have our team get back to you afterward. Lujan: It's been admitted by Facebook that you do collect data points on non-[Facebook users]. My question is, can someone who does not have a Facebook account opt out of Facebook's involuntary data collection? Zuckerberg: Anyone can turn off and opt out of any data collection for ads, whether they use our services or not but in order to prevent people from scraping public information ... we need to know when someone is repeatedly trying to access our services.

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