Microsoft’s MoodScope is a “sensor” that measures a smartphone user’s mental state. It analyzes an enormous array of interactions including app usage, phone calls, emails, text messages, browsing history, and geographic location — thousands of data points each day. 32 study participants used the system for two months, and completed mood self-assessments to gauge the accuracy of the software. The app was able to guess someone’s mood with 66% accuracy. When the software was “calibrated” for an individual user, accuracy increased to 93%.