Ranking of cities according to public health criteria: pitfalls and opportunities.

Popular magazines often rank cities in terms of various aspects of quality of life. Such ranking studies can motivate people to visit or relocate to a particular city or increase the frequency with which they engage in healthy behaviors. With careful consideration of study design and data limitations, these efforts also can assist policymakers in identifying local public health issues. We discuss considerations in interpreting ranking studies that use environmental measures of a city population's public health related to physical activity, nutrition, and obesity. Ranking studies such as those commonly publicized are constrained by statistical methodology issues and a lack of a scientific basis in regard to design.