"The data used by the researchers was anonymized, meaning it did not carry identifying markers like a user name, so the individuals conducting the searche

"The data used by the researchers was anonymized, meaning it did not carry identifying markers like a user name, so the individuals conducting the searches could not be contacted." As when AOL or Yahoo released their anonymized data set, it is often easy to take someone's search history and work backwards to find out who they are. How can they ensure that personally identifiable information has been scrubbed 100% from all queries? Maybe a user searched a courier tracking number, and that info can now be looked up on the courier's site and tracked back to their home or office address. Each additional piece of info gets you one step closer to identifying who they are. Yet one more reason to use DuckDuckGo for your general search needs.