From ProPublica’s Electionland
Written by Jeremy B. Merrill

More than 16,000 people have participated in our project to collect and analyze political ads on the social media platform during the midterm elections this year.

Since we launched our Facebook Political Ad Collector project in fall 2017, more than 16,000 people have participated in it. They all agreed to install a browser plug-in that anonymously sent us the ads they see when they browse Facebook. We used that data to understand and report on how political messaging on Facebook works, and how the system is being gamed to manipulate the public discourse.

Although the number of users is large, over the summer we noticed a potential snag: We were receiving more ads from Democrats and progressive groups than from Republicans or conservative groups. Our hunch was that this was because we had more liberal participants than conservatives ones.

We tried a number of things to make our ad collection more diverse: to start, we bought our own Facebook ads asking people across a range of states to install the ad collector. We also teamed up with Mozilla, maker of the Firefox web browser, for a special election-oriented project, in an attempt to reach a broader swath of users.

But because we made the Political Ad Collector almost completely anonymous, we couldn’t say much definitively about the audience. We also couldn’t know for sure how much of the skew in our findings was because of the people who participated in the project and how much of it was because left-leaning groups used Facebook advertising more than (or differently than) conservative groups.

To dig deeper, we partnered with some academic researchers and a research firm called YouGov to create a panel of users from across a wide spectrum of demographic groups and political ideologies who would agree to use a special version of the ad collector plug-in that was less anonymous. For these users, we had a unique ID that was tied back to data about them provided to us by YouGov — demographics, political leaning, race, state of residence, but not name or address.

See full article here.