"Secret Data" and Differential Privacy

See Cochrane's original post and followup.  The followup mentions the idea of differential privacy as a "technology" that may provide a potential solution when there are issues of data confidentiality.   Actually differential privacy is much more than an off-the-shelf technology.  Or much less, depending on your view, as it's very much an active and fascinating research area in algorithmic game theory.  Dwork and Roth (2014) provide a fine overview.  (Aaron Roth is my Penn colleague.)