Birthday + Gender + Zip code can uniquely identify anyone in the United States with 87% accuracy (Research by Dr. Latanya Sweeney). Dr. Sweeney is now a professor at Harvard University and director of their data privacy lab.
L. Sweeney. Simple Demographics Often Identify People Uniquely. Carnegie Mellon University, Data Privacy Working Paper 3. Pittsburgh 2000.
Comprehensive research and reporting about the data collection marketplace, including:
What kinds of data companies collect and infer about you
Major data companies you’ve never heard of, though they likely have quite a bit of data about you
How companies can track you across devices
How companies can link you digital information with your offline identity
And much more.
Corporate Surveillance in Everyday Life. How Companies Collect, Combine, Analyze, Trade, and Use Personal Data on Billions. A Report by Cracked Labs, Vienna, June 2017. Author: Wolfie Christl. Contributors: Katharina Kopp, Patrick Urs Riechert. Illustrations: Pascale Osterwalder. Web link here.
Statistics about the reach of Oracle’s data marketplace: “includes more than 30,000 data attributes on two billion consumer profiles” — taken directly from Oracle press release published in 2017. Press release has been removed but archived version available here:
Examples of Additional "linking services" that match online data to offline, real-world data:
“ID Graph” by Oracle
“IdentityLink” by Acxiom
“Abilitec Link” by Acxiom
“LiveRamp” by Acxiom
Facebook, Twitter, and Google also have “upload and match” services whereby companies can upload their private real-world customer data and have it matched with digital users on each of the platforms.