Recently, MSNBC warned “Beep! Beep! That creeping commute is hurting your health,” citing a newly published article entitled “Commuting Distance, Cardiorespiratory Fitness, and Metabolic Risk” by Dr. Christine Hoehner et al. The health study finds a statistically significant correlation between commute length and poorer scores on several health indicators, including high blood pressure, obesity, and physical exercise. It is plausible that people with long commutes (i) have less time available for exercise and (ii) are stressed while sitting in traffic, both of which contribute to poor health.
However, the study acknowledges that it does not account for socioeconomic status, which may itself be correlated with health and average commute time. Hoehner and her colleagues note (in somewhat muted and academic terms) “…some residual confounding may be present because of other unmeasured socioeconomic variables (e.g., occupation and income)” (page 6).
Basically, (i) since lower socioeconomic status is likely correlated with poorer health and (ii) if poorer workers also have longer commutes, the correlation between commute length and health is possibly observed because lower socioeconomic standing simultaneously causes both moving to areas that require longer commutes and living less healthy lives. While a mainstream news outlet may be inclined to oversell the punchline of new research, the underlying report and analysis often includes other important information to consider.