It is based on the principle that high levels of one attribute amongst one's peers can have spillover effects on an individual.
"This social multiplier can also be thought of as a ratio ∆P/∆I where ∆I is the average response of an individual action to an exogenous parameter (that affects only that person) and ∆P is the (per capita) response of the peer group to a change in the same parameter that affects the entire peer group.
[5] Xiaodong Liu et al. have found that there is a multiplier effect for juvenile delinquency in schools.
It is well documented that factors like income and education have strong positive correlations with many aspects of health.
This challenge to the identifiability of social multiplier effects is known in econometrics as the "reflection problem", following an influential 1993 paper by Charles F. Manski.