Sensitive data combinations

This post is my first attempt to tackle the thorny issue of data which is not core personally-identifiable information (PII) but which, in some combinations, is enough to identify an individual. I’ll call this type of data combination-PII (or combo-PII), and such a combination in a specific search a ‘profile’, for this purpose of this discussion.

Combo-PII is reference data that describes living persons

This type of data is usually called ‘reference’ data by database specialists. This is the background data that structures our picture of a person using categories, such as the city and country we live in, our age range, consumer choices (e.g., electricity provider), and similar data. Each of these values, taken by itself, is not enough to identify a person. Many such values taken together can, in some cases, either identify the data subject with certainty, or narrow the number of possibilities enough for subject to be guessed, or combined with other data to produce a match. Continue reading “Sensitive data combinations”