Over the last 15 years, mobile devices have become a method of interest for collecting health related information and administering treatment. Research based on these methods has increased considerably, and includes one-time cross-sectional survey, longitudinal data collection and randomized clinical trials. Data from these studies include objective measures, data based on smartphone and wearable sensors, ecological momentary assessment and standard self-reported survey. A perfect example of this work is the NIH Common Fund supported All Of Us study. Because of the nascence of this method of data collection, we are just beginning to learn the promise and limitations of this data. In my presentation, I will describe six digital studies: two large scale clinical trials, three longitudinal studies and one meta-analysis of several health-related digital studies. I will talk about recruitment, retention and data completeness, population representation, and will end with a discussion around the ethical management of such data.