Bayesian Mixed-Effects Location Scale Models for the Analysis of Objectively Measured Physical Activity Data from a Lifestyle Intervention Trial

• Activity Number: 161
• Type: Topic Contributed
• Date/Time: Monday, August 4, 2014 : 10:30 AM to 12:20 PM
• Sponsor: Korean International Statistical Society
• Author(s): Juned Siddique*+ and Donald Hedeker and Bonnie Spring
• Companies: Northwestern University and University of Illinois at Chicago and Northwestern University
• Keywords: accelerometry ; random effects ; Bayesian ; physical activity ; lifestyle ; clinical trial

Abstract

We describe a Bayesian mixed-effects location scale model for the analyses of physical activity as measured by accelerometer using data from a randomized lifestyle intervention trial of 204 men and women. We model both the mean and variance over time as a function of subject-specific random effects and time varying covariates. Our model allows us to measure how covariates can influence both the mean and the variance of physical activity over time. It also allows us to measure whether changes in variability over the course of the study are predictive of treatment relapse.