Random Assignment of Intervention Messages for Developing Personalized Decision Rules to Promote Physical Activity (RandomAIM)

Our goal is to develop personalized decision rules for selecting the frequency, timing, and content of messages to promote physical activity. The objective of this project is to develop personalized dynamical models of physical activity (PA) under different weather and temporal conditions as well as in response to different types of intervention messages. This approach relies on having extensive observations within the person under varying conditions to develop a dynamical model of how different conditions interact with each other to predict how behavior changes in response to text messages. Complementary sub-models will be estimated for each participant to describe their behavioral responses under different weather conditions. Healthy but insufficiently active young adults (n=80) will wear an activity monitor and receive a variety of randomly-timed and randomly-selected notifications via smartphone. GPS coordinates at the time of messages delivery and receipt are recorded and used to look up weather indices at that location at that time. The work is exploratory/descriptive as we will be developing models to describe participants' responses to messages under different weather conditions. This work is needed to develop the decision rules for a subsequent behavioral intervention that will be developed and tested in a future project.