Your Facebook News Feed is a hodgepodge of information: some of it you love, some of it you hate, and some of it may just make you scratch your head. The average user's News Feed has around 1,500 possible stories filtered through per day, according to Lars Backstrom, engineering manager for Facebook's News Feed ranking. But only 20% of them actually make your feed.
So how does Facebook determine which 20% you see?
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The social network attempted to answer that question at a special event at its Menlo Park, Calif., headquarters on Tuesday, explaining how the system has moved from manual knob-turning during the feed's early days (they used to increase or decrease the number of photos or status updates you'd see based on anecdotal feedback from users) to the systematic algorithm that determines what you see today.
Facebook reiterated its oft-stated goal: to give users a "customized newspaper" highlighting the stories it assumes users will find most interesting. The process assigns each new story a score, placing the highest scoring stories at the top of the feed.
Scores are determined using a number of factors, such as the relationship you have with the user who posted it, the number of comments, the number of shares, and the number of likes that the story has accumulated.
Previously, each time a user refreshed their feed, new stories automatically moved to the top of the feed — even if they had a lower score than stories previously displayed. A change in the ranking process now enables older stories (stories that may have been posted earlier in the day but the user never actually scrolled through) to join the "new" stories at the top of your feed.
The hope is that relevant posts that may not have been at the top of your feed during your first scan, can still resurface and won't be buried by new, less relevant content.
The change has been implemented on Facebook's web version, but it's still being rolled out on mobile devices, says Backstrom. This new strategy has created an uptick in user engagement, he adds. A recent study by Facebook found that this new ranking system led to a 13% increase in stories read, and a 5% increase in interactions (Likes, shares, comments).
Another change to the algorithm looks at a user’s last 50 interactions, putting a higher priority on the friends or pages they’ve interacted with most recently. This change is not yet rolled out over all devices, says Backstrom.
Backstrom says the new “story bumping” feature does not affect ads on News Feed, confirming the ad system is completely different than the one determining News Feed’s user-created content. It is still common for ads to show up on your news feed over multiple days if they are relevant.