Speaking of analysing large numbers of health trackers, there was that time Jawbone used its data to figure out which areas were woken up by an earthquake: http

Speaking of analysing large numbers of health trackers, there was that time Jawbone used its data to figure out which areas were woken up by an earthquake: https://jawbone.com/blog/napa-earthquake-effect-on-sleep/ https://jawbone.com/blog/napa-earthquake-effect-on-sleep/