"The social influence component is an important component, and too much attention may have been focused just on the built environment," said Ms. Datar, a senior economist at the Dornsife Center for Economic and Social Research at the University of Southern California. "That doesn't seem to be where the answer is, that you can build all these parks and things. There's the social influence aspect that has to be addressed as well."
Ms. Datar, with co-author Nancy Nicosia of the Rand Corp., set out on a study that evaluated how location influences obesity rates in military families, who often move around the country because of where they are needed and not by personal choice.
"To be honest with you, we were not expecting to find a social contagion," said Ms. Datar, adding that the study originally was meant to look at how the built environment influenced obesity rates in neighborhoods.