“…Clark and Lohéac, 2007), by using various peer characteristics -such as percentage of peers whose parents smoke, who live with both biological parents, or who report having easy access to cigarettes or alcohol at home -to instrument for peer behaviour (e.g. Ali and Dwyer, 2009;Ali et al, 2011;Card and Giuliano, 2013;Halliday and Kwak, 2012), or by exploiting the mobility of school friends, either from switching schools or from graduating (Eisenberg, 2004). Where they look at cannabis use, these studies tend to report positive and significant, and in the case of Ali et al (2011) quite large, peer effects.…”