[6][7][8] Her best known academic work is on the theory of k-anonymity, and she is credited with the observation that "87% of the U.S. population is uniquely identified by date of birth, gender, postal code".

[11] In 2001, Sweeney was awarded a Ph.D. in computer science from the Massachusetts Institute of Technology, the first African American woman to do so.

[18] In her landmark article “Only You, Your Doctor, and Many Others May Know,”[19] Sweeney discussed her research project in which she was able to locate and match identities and personal health records through a number of methods.

Such methods, as she explains in depth later on, include looking at public health records from hospitals and newspaper stories.

Towards the end of the article, Sweeney touches upon the different approaches of how she analyzed and matched the data, either through using computer programs or human effort.

Sweeney found that 87% of the US population in a censorship dataset, can be identified by combining data attributes which are known as quasi-identifiers.