Tracing you by the hole you make in the world
July 9, 2011 3:24 PM Subscribe
How many people would have to sign up for facebook before facebook can infer the existence of the rest?
posted by Diablevert to Computers & Internet (6 answers total) 5 users marked this as a favorite
This is something that I've been wondering about lately, and I suspect there's math that could tell me: how many people have to sign up for facebook before facebook could effectively profile the remainder of the people who haven't joined its network?
That is to say, it's known that sites with like buttons have cookies that track IP addresses, and when facebook collects emails from people who join it cross-checks and retains emails from people who haven't joined. Both of these practices are so that, if you then go to sign up later, they can link you up with this info, hooking you up with friends who's already joined and sites you might like and so forth. Also, they have facial recognition software built in to their photo ap and people can tag you in a photo even if you don't have an account --- I understand that these photos can also then be picked up as part of your profile if you join at a later date.
So I'm thinking, even if I don't have a facebook account, at this point, given how many of my friends and family have joined, it would probably be possible to infer my existence from my email address turning up in their address books and photos of me on their profiles. In effect I have been captured by the network even though I don't have an account.
What I'm wondering is, what percentage of people would have to join facebook before FB could effectively capture the remainder in this way? Granted that there are exceptions --- people who aren't that linked in to society itself in ways that would make it less likely they would be captured (infants, homeless people, the elderly, etc.). And obviously much of this depends on the connected to the internet-ness of one's real life society as a whole --- a country with a big chunk of it population living in remote villages, etc., is not going to be well captured (or not for some time). So absolutely 100% of people is an impossible goal.
But for, say, the English-speaking and/or developed world, I'm wondering what the tipping point would be. Is there anyone who's aware of any branch of mathematics/social science/computer science that's looked at this type of network effect?