There are many different ways that aspects of the social and physical environment can affect a person’s health. For example, body mass index and chronic disease are associated with the walkability of the area where a person lives. Spending more time near fast food outlets is associated with greater saturated fat intake. Being present in neighborhoods with more decay and disorder is related to increased risks for assault. The studies that identified these associations all link individuals to their neighborhood environments in some way. But if the researchers had used different approaches to make this link, would they have arrived at the same findings?
Christopher Morrison and his colleagues from the Prevention Research Center in Berkeley, CA, published a paper in Epidemiology that addressed this question. They used one month of GPS data for 231 adolescents aged 14 to 16, and tested whether exposure to retail alcohol outlets was associated with increased alcohol consumption. The group used three different approaches to link the environmental condition (alcohol outlets) to the individuals. They measured exposure around the person’s home, around the places they attended most frequently, and around the full GPS route path.
The researchers found that the different measures of exposure to alcohol outlets were, at best, moderately correlated, which means they probably all measure different constructs. Perhaps more importantly, the different measures produced different associations with alcohol outlets—in some cases the exposure was positively related to the outcome, and in others there was no association. It seems the way we measure individuals’ exposures to environmental conditions could very substantially affect the results of a given study.