The sources

How Companies Learn Your Secrets

Duhigg, Charles · New York Times Magazine · 19 February 2012

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The source behind the Target pregnancy-prediction story, used to show how ordinary shopping data can reveal something intimate before a person has chosen to say it aloud.

Cited in

Duhigg, Charles. "How Companies Learn Your Secrets." New York Times Magazine, 19 February 2012. (Target pregnancy prediction story)