Like it or not! – Facebook’s ability to track web behavior (with Luis Aguiar and Jörg Claussen)
The online advertising industry is relying heavily on tracking user behavior to offer relevant advertisements. This tracking is increasingly carried out across many websites, allowing advertisers to get a better picture of user preferences, but creating increasing privacy concerns. However, little is known how much trackers really know about individual users. We measure how much of an individual's Internet activity can be monitored by Facebook, which runs one of the biggest tracking network through their like and share plug-ins. Based on individual-level clickstream data of 24,000 German Internet users, we show that at least 10% of website visits of Facebook users can be tracked by Facebook. This ratio is lower for users that do not have Facebook accounts, but not zero. We characterize user's benefits from giving up their privacy to Facebook by using variation in how much they use Facebook.