Predicting User Engagement in Longitudinal Interventions with Virtual Agents

Longitudinal agent-based interventions only work if people continue using them on a regular basis, thus identifying users who are at risk of disengaging from these applications is important for retention and efficacy. We develop machine learning models that predict long-term user engagement in three longitudinal virtual agent-based health interventions. We achieve accuracies of 74% to 90% in predicting user dropout in a given prediction period of the intervention based on the user's past interactions with the agent. Our models contain features related to session frequency and duration, health behavior, and user-agent dialogue content. We find that the features most predictive of dropout include number of user utterances, percent of user utterances that are questions, and the percent of user health behavior goals met during the observation period. Ramifications for the design of virtual agents for longitudinal applications are discussed.