What is the Facebook friends algorithm?
May 19, 2012 11:32 PM   Subscribe

I'm trying to figure out the Facebook friends algorithm. Because I'm nosy.

So, I know that Facebook never gives away the game when it comes to who looks at your profile, but I'm curious. In my friends list (on Timeline), there is definitely some sort of hierarchical order, most of my good friends being at the top. When I look at other friends' lists, THEIR good friends are at the top (sometimes me, hurrah!).

This leads me to believe it's a "people you interact most with" algorithm, which seems straightforward. However - some people that I rarely interact with, when I click on their list, have ME very near/at the top. Which makes me think, huh. In what sort of way does Facebook think WE have been interacting? i.e. are these people 'stalking' me? (Not using this term seriously of course).

I thought that maybe the friends list is a subjective list tailored to the viewer, rather than an objective list, but this seems not to be the case. Often on friend's lists, people who I have never interacted with/viewed their profile are at the top, and they're people I know to be good friends with the person.

I'm just curious, and have too much time in my hands, I know. But it seems like there is some sort of secret information that Facebook is subtly giving away here and I want to know what it is, dammit. Does anybody have any insider information?

(ps. I'm talking about the main list after 'mutual friends'.)
posted by rose selavy to Computers & Internet (9 answers total) 5 users marked this as a favorite
Have you considered a 2nd degree connection (for lack of a better term). In this example:

This leads me to believe it's a "people you interact most with" algorithm, which seems straightforward. However - some people that I rarely interact with, when I click on their list, have ME very near/at the top.

In your circle you could be a popular person to interact with. So even if you don't interact with this person, this person is friends with a lot of people who you do interact with and you're a popular choice for them. So it's inferable (from FB point of view) that you would be a popular contact for people who are in the same circle but you don't interact with.

This is all like the "Target knows I'm pregnant" issue. Given a large enough view of the data, and enough computing power to process it, trends like this become obvious.
posted by sbutler at 11:59 PM on May 19, 2012

Well, it's obviously algorithmic, so I wouldn't place too much ultimate credence on it. I know on FB people who actually actively use the site and thus like/comment/tag much more than other people I know better in RL migrate into my own "Close Friends" list. So what it represents needs to be understood in purely Facebookian terms.

You also need to keep in mind that FB keeps track of a lot of stuff you never even know about, like who clicks on your photos to see them full size, even if they never like/comment/share overtly. They also know about interactions with mutual friends that you might not notice, mutually liked pages, mutually visited places, that sort of thing.

As for specifics, I'm sure it's constantly being tweaked. But FB has been pretty open that it's based on interaction generally. That is, after all, all they have on you.
posted by dhartung at 11:59 PM on May 19, 2012

You and your friends toward the top all like and comment on the same or similar things. When you look at someone else's friend list, likely you have some social proximity that may not be immediately apparent.

10 Top Friends
Relational Algebra
posted by rhizome at 1:24 AM on May 20, 2012 [2 favorites]

Bit of a self link, since I'm involved with this project, but if you want to know the legal aspects on the "Target knows you're pregnant" issue: Should Target Tell Your Loved Ones You Are Pregnant, Or Should You?
posted by twiggy32 at 1:28 AM on May 20, 2012 [4 favorites]

Thank you for the Quora link. The last post on that page is thought provoking, especially:

"It's amazing how the observable changes in the visual representation of your friends list following your own varied user action has the ability to manipulate your thoughts, emotions and subsequent interactions... Even the way you uniquely hypothesis the function of this element has implications on your future, well, on your thought patterns, which is essentially your future."

I hadn't seen the Target issue before either, thanks.

What strikes me is the seemingly one-sided nature of this algorithm, in that I am at the very top of a friend's list, and they aren't even in the first 50 or so on my list. How would that work? Surely this algorithm calculates a concept of a mutual relationship?
posted by rose selavy at 1:42 AM on May 20, 2012

The relationship calculations are asymmetrical and done twice for each pair of friends. You're at the top of your friend's list because the ranking uses the context of you two to calculate the rest of the list. However, it can be said to be one-dimensional in that everybody has a separate "view" on every friend list that they look at. Your friends see themselves at the top of your friend list when they look at it, with a different concomitant order of your other friends.
posted by rhizome at 2:31 AM on May 20, 2012

At the top of your list are the people you stalk the most.
posted by inkypinky at 2:36 AM on May 20, 2012 [1 favorite]

Inkypinky, this is why I'm confused. The people I stalk aren't near the top of my list!
posted by rose selavy at 3:29 AM on May 20, 2012

What do you mean by "stalk?" I don't think profile views are part of the calculation, just combined contributions to the FB database (comments, posts, likes, shares, pix, etc...FB's lifeblood). They could certainly include stalks, but turning on pageview calculations for a userbase the size of FB would be unwieldy to say the least. Like, suddenly they have to start processing a terabyte per hour (napkin number) of logging just for profile views.
posted by rhizome at 12:22 PM on May 21, 2012

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