By Colin Stretch, Facebook General Counsel

Last week we met with Chairman of the U.S. Senate Commerce Committee John Thune to describe our investigation in response to anonymous allegations of political bias in our Trending Topics feature and to discuss the preliminary results of our work. Today, we sent Chairman Thune a follow up letter setting out our findings and conclusions. As we explain there, suppressing political content or preventing people from seeing what matters most to them is directly contrary to our mission and our business objectives and the allegations troubled us deeply. We are proud of the platform and community we have created, and it is important to us that Facebook continues to be a platform for all ideas.

As soon as we heard of these allegations, we initiated an investigation into the policies and practices around Trending Topics to determine if anyone working on the product acted in ways that are inconsistent with our policies and mission. We spoke with current reviewers and their supervisors, as well as a cross-section of former reviewers; spoke with our contractor; reviewed our guidelines, training, and practices; examined the effectiveness of our oversight; and analyzed data on the implementation of our guidelines by reviewers. We also talked to leading conservatives, to gain valuable feedback and insights.

Our investigation has revealed no evidence of systematic political bias in the selection or prominence of stories included in the Trending Topics feature. Our data analysis indicated that conservative and liberal topics are approved as trending topics at virtually identical rates. We were also unable to substantiate any of the specific allegations of politically-motivated suppression of particular subjects or sources. In fact, we confirmed that most of the subjects mentioned in media reports were included as trending topics on multiple occasions.

At the same time, our investigation could not fully exclude the possibility of isolated improper actions or unintentional bias in the implementation of our guidelines or policies. As part of our commitment to continually improve our products and to minimize risks where human judgment is involved, we are making a number of improvements to Trending Topics, including:

Updated terminology in our Guidelines to make them more clear

Refresher training for all reviewers that emphasized that content decisions may not be made on the basis of politics or ideology

Additional controls and oversight around the review team, including robust escalation procedures

In addition to these operational efforts, we are also making the following improvements to the product and tools:

We will no longer rely on lists of external websites and news outlets to identify, validate or assess the importance of particular topics. This means we will eliminate the “Media 1K” list, the list of RSS feeds used to supplement the algorithm that generates potential trending topics, and the top-10 list of news outlets.

We are also removing the ability to assign an “importance level” to a topic through assessment of the topic’s prominence on the top-10 list of news outlets.

We will expand our Help Center content on Trending Topics to provide more information about this feature and how it works.

We appreciated the opportunity to discuss these issues with the Chairman. This process has helped us to identify valuable improvements to our service. These improvements and safeguards are designed not only to ensure that Facebook remains a platform that is open and welcoming to all groups and individuals, but also to restore any loss of trust in the Trending Topics feature.

We will continue to work to improve the feature, as well as to seek feedback from people who use our service to make sure we keep Facebook a platform for all ideas.