Abstract

In the spring of 2020, we published AdObserver, a browser extension for anonymously crowdsourcing data about ads on social media. Over the past year, 17,000 users have downloaded AdObserver for Chrome or Firefox. During the 2020 US election period, we were able to collect observations of tens of thousands of ads every day. We publicly released the political Facebook ads we were able to identify, including the ad targetings. We present a case study of AdObserver and review initial results. Data collected via our browser extension has been instrumental to our discovery of security vulnerabilities and errors in both Facebook and Google’s systems for ensuring ads comply with platform policies and the law.

We also discuss important considerations for researchers considering collecting data in this way and specific best practices for projects attempting to use browser extensions to crowdsource data while protecting the privacy of users who donate data.

RECORDING : Please note, this event may be recorded and may be available after the event for an indeterminate period under a CC BY -NC-ND license. Audience members should bear this in mind before joining the webinar or asking questions.