“…Homophily can also be driven by preferences: students may prefer to associate with other students of the same age since their interests and maturity will be similar. The role of biases in contact as a source of homophily is discussed by Allport (1954), Blau (1977), Feld (1981), Rytina and Morgan (1982), and the role preferences for associating with individuals with similar traits, behaviors, or backgrounds is discussed by Cohen (1977), Kandel (1978), Knoke (1990), and Currarini, Jackson and Pin (2008 and Bramoullé and Rogers (2009). There are also other reasons that homophily might arise, including competition among groups (Giles and Evans (1986)), social norms and culture (Carley 1991)), institutional and organizational pressures (Meeker an Weiler (1970), Khmelkov and Hallinan (1999), Kubitschek and Hallinan (1998), Stearns (2004)).…”