In a blog post detailing the new experiment, Uber chief security officer Joe Sullivan writes that "gyrometers in phones can measure small movements, while GPS and accelerometers show how often a vehicle starts and stops, as well as its overall speed." The company told The Guardian that it has been running this experiment in Texas since late 2015, and that it plans to run more experiments to monitor driver and passenger behavior. In its official announcement, Uber describes the move as a way to verify negative driver ratings or feedback from passengers. For example, if a driver gets a low rating and is accused of speeding or driving unsafely during the ride, Uber could look at the driving data to determine what happened.Though Uber could reserve looking at the data only when there is a complaint, nothing prevents it from actively monitoring its drivers to regularly conduct quality control and make sure there's no unsafe behavior.