From The Wall Street Journal:

Computer scientists at Carnegie Mellon University concluded that a dozen or so popular Android apps collected device location – GPS coordinates accurate to within 50 meters – an average 6,200 times, or roughly every three minutes, per participant over a two-week study period.

The researchers recruited 23 users of Android version 4.3 from Craigslist and the Carnegie Mellon student body. Participants were allowed to use their own choice of apps after installing software that noted app requests for a variety of personal information; not only location but also contacts, call logs, calendar entries, and camera output. They weren’t told the purpose of the study and were screened to weed out people who had a technical background or strong views about privacy.