More than 25% of adults in the U.S. are obese,1 contributing to 300,000 deaths and costing the U.S. healthcare system $147 billion annually.2 A range of institutions, from federal governments to local nonprofit agencies, have implemented policy and built-environment changes in efforts to reduce obesity and increase physical activity. A challenge in evaluating the success of policy and built-environment change is the capacity to capture a priori physical activity behaviors and to eliminate researcher and respondent bias in assessing postchange environments.
