Evidence of Large-Scale Social Interactions in Mammography in the United States

This paper examines the extent of social interactions in an individual’s decision to undergo mammography. Using Behavioral Risk Factors Surveillance System surveys from 1993 to 2016, the effect of other female screening behavior on an individual’s decision to have a routine breast cancer screening was measured by calculating the size of a so called “social multiplier” in mammography. A vector of social multipliers was estimated in the use of mammograms in the past 1–2 years by taking the ratio of group-level effects of exogenous explanatory variables to individual-level effects of the same variables. Peer groups were defined as same-aged women living in the same state. Three age groups of women were considered: 40–49, 50–74, and 75 and older. Several econometric approaches were used to analyze the effect of social interactions on mammography use, including ordinary least squares, fixed effects, and split-sample instrumental variable. For all women, evidence was found of social interactions associated with individual’s education, employment, and poor health. In addition, number of age-group-specific social multipliers was found. The strongest evidence of spillover in mammography was found for women ages 75 and older. Policy makers should be aware that, in the presence of a social multiplier, the value of any type of screening intervention is higher than the one that would be measured at the individual-level.