neither immediate neighbors nor geographic distance modify alcohol consumption behavior. If shared exposure (such as proximity to liquor stores or local economic hardship) were key, the effects would decay with distance. Moreover, since the models control for a principal's prior drinking status, it is possible to account for sources of confounding that are stable over time (such as childhood exposures or genetic endowment). Finally, it is possible to control for a contact's prior drinking status, thus accounting for a possible tendency of drinkers to form ties among themselves. To help further control for homphily and environmental exposures, the authors are currently pursuing follow-up studies using econometric and experimental methods.
