Facebook to update Trending Topics
Facebook has announced changes to the way it runs its Trending Topics feed, following an internal investigation.
There will be more training for staff and the feed will no longer rely on a list of news organisations, including the BBC, Washington Post and Buzzfeed News, to validate subjects.
The feed, which lists popular headlines along with a brief description, has been accused of political bias.
However, Facebook's report found no evidence of this.
Facebook general counsel Colin Stretch said the investigation analysed 3,000 reviewer decisions following allegations that conservative issues were being suppressed.
The site was accused by anonymous former employees of tampering with its Trending Topics feature, promoting "progressive" views and websites over content presenting views from the American right.
Current and former staff were also interviewed by the firm.
The findings were revealed in a 12-page letter, addressed to US Senator John Thune but also published online, in response to Mr Thune's questions about the workings of Trending.
The Trending Topics feed currently works as a mixture of AI and human input, with potential subjects being suggested via algorithm and then reviewed by staff.
They are a mixture of popular subjects discussed on the social network and sourced from 1,000 media organisations. There was also a list of 10 organisations used to determine importance.
However, "as much as half" of the topics suggested algorithmically are rejected "because they do not make sense at the time or are duplicative", Mr Stretch said.
So-called "stale topics" - events still popular in discussions after two days but with no new developments - and "junk hashtags" - popular topics not related to actual events - are also sidelined, he added.
Topics with sources in foreign languages may also not be included on the grounds that the team may be unable to identify them, Mr Stretch explained.
The report did find that historically some topics that were discussed over a long period of time did not show up algorithmically.
For example, hashtags relating to the Black Lives Matter campaign failed to appear in December 2014 and were not manually inserted by the Trending Topics review team either.
However, the topic "Ferguson", which related to the police shooting of Michael Brown in Missouri, was added to compensate for this, wrote Mr Stretch.
Some Facebook users have queried the relevance of Trending Topics, which at the time of writing range from a "reported wardrobe malfunction" by US socialite Paris Hilton to the results of the Austrian presidential election.