A hybrid mass participation approach to mobile software trials.

User trials of mobile applications have followed a steady march out of the lab, and progressively further ''into the wild', recently involving ''app store'-style releases of software to the general public. Yet from our experiences on these mass participation systems and a survey of the literature, we identify a number of reported difficulties. We propose a hybrid methodology that aims to address these, by combining a global software release with a concurrent local trial. A phone-based game, created to explore the uptake and use of ad hoc peer-to-peer networking, was evaluated using this new hybrid trial method, combining a small-scale local trial (11 users) with a ''mass participation' trial (over 10,000 users). Our hybrid method offers many benefits, allowing locally observed findings to be verified, patterns in globally collected data to be explained and addresses ethical issues raised by the mass participation approach. We note trends in the local trial that did not appear in the larger scale deployment, and which would therefore have led to misleading results were the application trialed using ''traditional' methods alone. Based on this study and previous experience, we provide a set of guidelines to researchers working in this area.