At a hackathon back in 2013, someone mentioned analyzing Medicare claim data to find impossible or improbable scenarios, like a doctor performing two lengthy procedures on the same day at hospitals 500 miles apart.
There was a famous case in LA of a couple of doctors working impossible shifts (more than 24 hours in a day, or 24 hours a day for over a week straight):
http://articles.latimes.com/2005/apr/26/local/me-kingdrew26
Eventually the facility was closed and some of the administrators were canned.