- Ermagun, Alireza, and Levinson, D. (2015) “Transit Makes you Short”: On Health Impact Assessment of Transportation and the Built Environment. Journal of Transport and Health. [doi]
The study looked at how researchers draw exaggerated conclusions based on their data
While many click-bait articles have headlines that claim using public transportation has a significant impact on health, a University of Minnesota study, which explored the correlation between transit and public health, found that there was no significant evidence showing that using public transit improves health.
“For the last 10-15 years, people have been saying they want people to be walking or using transit because there is a significant health benefit,” said David Levinson, University transportation studies senior research associate and co-author of the study.
“It may or may not be true, but it’s a very weak correlation.”
There is an idea that commuters are a more healthy population due to the fact that they use public transit, Levinson said.
Transit is often associated with walking or biking. Previous studies have found that citizens in areas with more transit options have a lower BMI.
But using BMI for that conclusion doesn’t account for commuters who may eat fast food every day or substitute buses and trains for walking from place to place, Levinson said.
Ultimately, the researchers found transit did not have a significant impact on public health.
Alireza Ermagun, University urban and regional planning Ph.D. candidate [sic – he got a PhD in Civil Engineering, he was also a MURP] research assistant and co-author of the study, said he wanted to point out problems with associating insignificant correlations to data and making assumptions not backed up by sufficient research.
Researchers often rely on data they already have to draw conclusions because research is expensive and difficult to compile, he said.
For example, the researchers analyzed the height of transit users relative to their location because other researchers often correlate travel method and body mass index. They found that people were shorter in locations like cities, where transit was more readily available.
This could justify the claim that transit makes you shorter, he said.
“People are too quick to use these results to draw conclusions,” Levinson said.
But Ermagun said he hopes this study will caution future researchers from making assumptions about their data based on exaggerated connections.
“The result of this study helps people gain a clearer view,” he said. “It allows them to put these resources in a more effective direction.”
Elizabeth Wrigley-Field, [ed. note, apparently a real person] sociology assistant professor, said researchers often try to narrow down one specific way to improve public health.
“There is a lot of tendency in the topic of health to focus endlessly on things that actually make a small difference,” she said. “Like exactly what fruit we should be eating or what exercise we should be doing.”
Instead, Wrigley-Field said promoting larger-scale research would be a more efficient means to improving health through initiatives like reducing air pollution, combating poverty and eliminating food insecurity.
“The relative lack of attention to these topics isn’t a lack of knowledge,” she said, “but a lack of political will to talk about them.”