This document discusses using smartphone data to gain psychologically important insights. It summarizes past research that achieved 85% accuracy in predicting bipolar symptoms and 92% accuracy in detecting deception using location and usage data. The document then describes two of the author's own apps, ParkinsonEaston and Getting Log, which analyze location, movement patterns, and usage logs. It notes that recent changes in Android software now limit background access to location data, but discusses ways researchers can still gain insights while respecting users' privacy, such as focusing on places visited rather than movements.