Yesterday I published a story asking exactly how Facebook calculates who is shown in the friends box on the new profile pages. Well today Facebook rang me up and told me, or rather gave me some general statements explaining some of the factors that the algorithm might take into account when choosing whether Tom rather than Doris shows up in the list of friends on your wall.
Facebook choose people you are good friends with
First things first - the listing here has changed. It used to be relatively random, based on the alphabet, now it aims to select people according to how good friends you are with them. The idea is that you will be more likely to see your sister and your best friend popping up there than you will be to see Doris from school whose you never see or talk to on Facebook.
How it decides whether you are good friends with somebody
So how does Facebook decide whether you are good friends with let's say, Tom? Well, yesterday I was told by Facebook via an email that it bases the selection on public interactions you have had with those people in the past one and a half months.
That didn't seem to be the whole story - for example people I definitely hadn't talked to in the past 6 weeks had cropped up on mine - so today I got some more information and a slightly more convincing explanation.
The new explanation
The spokesperson today went into a little more depth, she told me that the algorithm that decides the friends list on your Facebook page uses a variety of other bits of data - but that all of them are public. She said that the algorithm was very complex and she couldn't know for certain everything it takes into account..
These are the things it probably takes into account:
>> the number of photos you are both tagged in [apparently this is upweighted a lot]
>> public interactions: how often you write on their on their wall, how often you share links with them, how much you comment on their photos or status updates
>> the number of friends you have in common
>> how long you have been friends [that would explain a few randoms from the past turning up on my wall yesterday]
She said that potentially it could be people that Facebook thinks you should interact with more: ie, you don't talk very much but have 60 friends in common (remember the "Why don't you reconnect with xx" feature? - it's a bit like that.)
What Facebook promises to never make public
Again she categorically stated that everything it takes into account is public: it won't take account of how often you chat to someone on Facebook chat, or how many private messages you send them or whether you poke them or not, nor as we speculated yesterday - how often you click on their profile.
The Facebook spokesperson reiterated that nothing on Facebook will ever make what you look at public - so browsing and er "stalking" are still an anonymous and safe activity.
When Facebook do track what you look at
However Facebook obviously do track where you click and what you look at for some things - for example for displaying relevant adverts to you and for determining what ends up in your newsfeed - I click more on John, I see John more - of course that's fine for me, because only I see that. The thing with top friends - is that it's not just me who sees that, it's everyone.. If it ever did emerge that some newsfeed-like algorithm got used to generate the top friends, then that would be breach of privacy. Currently though, we will take their word for it that they don't.
One final issue I have is that anyone I'm friends with can see my top friends, even if I have them on limited profile. So they may not be able to see how I interact with my friends -what I or my best friends write - but they could see which friends I am interacting with. . It's a small thing, still...
Any thoughts? We're keeping an eye on this for the meantime....