Sororities as Markets
Cornell’s Greek life makes up a large portion of the social scene on campus, as it has for most of Cornell’s creation. Every fall and spring, both male and female students rush, hoping to become a part of the tradition. Like in many other universities in America, the rush process for sororities and fraternities are vastly different, with the female students undergoing a much more systematic evaluation. Sororities very much follow the Gale-Shapley algorithm in the way they pick their new members. Following this matching theory, the chapters are the markets and the rushees are the buyers.
According to the Preferential-Bidding System Algorithm mentioned in my first article (which is a slightly modified version of the Gale-Shapley algorithm mentioned in the second), each group of sisters create an alphabetical list of their first-choice candidates and then a list of their second-choice candidates. The first choice candidates are only limited by the quota q, which is the number of women rushing divided by the number of participating sororities. The rushers themselves also create a list of their top 3 preferred sororities. A rusher can only join one sorority while a sorority can extend invitations to as many women as is their quota. Then the matching process occurs, and is repeated as many times is necessary for the sororities to fill their quota and all the women have a bid. The matching process is done so that each rusher gets into their top choice of sororities who find them acceptable.
The Gale-Shapley algorithm is related to matching partners with a single-sided matching mechanism rather than matching girls to sororities through a two-sided mechanism, but it follows the same logic. Theoretically, since the collective quota of the sororities is equal to the number of girls rushing, the process will eventually lead to a perfect match. However since the rules state that if a sorority does not receive q new members, or their total members including the new pledges q is less than the allowable chapter size, they can extend additional invitations to anyone rushing, this may not necessarily be true. Because of these rules, a sorority may not gain q new members while another sorority receives more than q. Still, the sorority rush process still follows the basic concepts of market matching
Sources:
http://www.pitt.edu/~daz1/sorority.html
http://www.nobelprize.org/nobel_prizes/economic-sciences/laureates/2012/popular-economicsciences2012.pdf