One set of data is not the issue. It's when you start compiling knowledge (I almost want to say "evidence") from multiple data sets that privacy is really inva

One set of data is not the issue. It's when you start compiling knowledge (I almost want to say "evidence") from multiple data sets that privacy is really invaded. Couple your anonymous dataset with the search histories of the people involved, and you'll likely get your answer. Or couple it to their travel info to see which hospital are they likely to have visited so regularly - does the hospital have a specialist diabetes or heart disease unit?