Data elements that in isolation look relatively innocuous can amount to a privacy breach when combined, warns Elizabeth Gorgue, privacy officer at the e-Government Office at the County of Santa Clara, Calif.
In the intelligence community, that's known as the "mosaic effect" -- when combinations of data tidbits produce a picture that wasn't apparent from the individual pieces.
As the delivery arm of a number of state and federal programs, the county collects and maintains an enormous amount of data on individuals, including information about their medical and mental health histories, criminal records, demographic profiles and welfare benefits. "The kind of information we gather and maintain leads us to be especially concerned about privacy," says Satish Ajmani, the county's CIO.
To ensure better privacy protection, the county has launched a major data classification project. Its goal is to locate and classify every bit of confidential information it manages in order to get a better handle on what's critical to privacy and what's not, Ajmani says.