Body Mass Index and Social Interactions from Adolescence to Adulthood

Scientific Conference (2018, July)

This paper proposes a novel approach to address identi fication of social endogenous e ects by generalizing the methods commonly used in standard dynamic panel data analysis to the peer e ffects setting ... [more ▼]

This paper proposes a novel approach to address identi fication of social endogenous e ects by generalizing the methods commonly used in standard dynamic panel data analysis to the peer e ffects setting. Our methodology shows to can estimate peer e ects free of the \re "reflection problem" in a dynamic context where individual- and group-specifi c unobservable e ects are controlled for. We apply a dynamic linear-in-means model for analyzing the importance of social ties for the body-weight-related behavior of US youth. We show that the main drivers of body-weight-related behavior are habituation and imitation eff ects. For individuals who were normal-weight during adolescence habits seem to be slightly enforced by imitative behavior: in this instance, for an 1% increase in average BMI we expect about 0:6% increase in individual BMI, whereas the coe cient for past BMI is 0:4%. Imitation e ffects, instead, explain most of the variation in the Body Mass Index of individuals who were overweight and obese during adolescence, signaling the presence of a social multiplier e ffect: for these two groups an increase of 1% in average BMI leads, respectively, to an increase of 0:2% and 0:4% in current BMI. [less ▲]