Participants will wear the portable monitoring device with heart rate monitor, pedometer and global positioning system (GPS) functions. A pre-calculated algorithm, developed using machine learning software will be used to predict challenging behaviour episodes 2-4 hours in advance of the event. Recent research has developed a best predictor model with a sensitivity of 82% and specificity of 42%, when averaged across two participants (in press). The device will communicate with a smart phone, via Bluetooth connectivity, when an event has been predicted.