Sorority Recruitment and Matching Markets
Though women going through sorority recruitment and medical students participating in residency matching do not share much in common at first glance, both of their futures hinge on similar matching markets. Medical students rank their top residency choices in their order of preference, and hospitals with available residency spots also rank the medical students that they would consider taking in order of preference. An algorithm then matches medical students with residencies, prioritizing the medical students’ choices in the matching process so that they are dissuaded from ranking their choices inaccurately. Similarly, under the preferential bidding system, women undergoing sorority recruitment rank their preferences for sororities in order during the last round of recruitment, and sororities rank the potential new members in their order of preference (Mongell and Roth 1991). The central Panhellenic organization on a given campus sets a quota for how many new members each sorority can take. Sororities that take fewer women than the quota specifies can begin an informal recruitment process after formal recruitment ends to recruit enough women to meet the quota, similarly to the second round matching that occurs for medical students and residency programs that are not matched initially.
Sororities submit two lists to the central Panhellenic organization; one contains the names of the girls that the sorority would most like to join, listed alphabetically. The other lists the sorority’s second choices in order of preference (Mongell and Roth 1991). While matching, the preferences of the potential new members are prioritized, just as the preferences of medical students are prioritized in residency matching. The matcher goes through potential new members alphabetically, and first checks if the sorority they ranked as their first choice also listed them on their first choice list. If so, they are matched, and the top woman from the sorority’s second choice list is moved to the first choice list (Mongell and Roth 1991). Women who are not matched with their first choice are set aside until matching with women’s first choices is complete. This process is then repeated for the remaining women using their second choice sororities, and later with the remaining women’s third choice sorority (Mongell and Roth 1991). If a woman doesn’t match with a sorority she listed on her preference list, Panhellenic will contact them to see if she would accept a bid from a sorority that has her on their first choice list, assuming that the sorority hadn’t yet reached quota.
Matches are stable if no potential new members are left matchless at the end and the quota is adhered to, in that the woman and the sorority would not both prefer a different woman/sorority to the ones they were assigned. However, in practice, matches are not always stable. For instance, if a sorority can take more new members than the quota specifies due to dwindling numbers of current members, this can lead to unstable matches. If the sorority has already been matched with the quota number of women, even if an additional woman is listed on the sorority’s first choice list (and the woman also ranks that sorority first), the woman will be assigned to her second choice sorority if she is on their first choice list, assuming the latter sorority has yet to reach quota. This would mean that even though the first sorority has more room and wants the woman (who also wants that sorority), they are not matched (Mongell and Roth 1991). Additionally, the woman could have been moved to her second choice’s sorority’s first choice list from the second choice list after some of their first choices were ruled out. Therefore, the woman’s match could be unstable.
Works Cited
Mongell, S. and Roth, A.E. “Sorority Rush as a Two-Sided Matching Mechanism,” American Economic Review, vol. 81, June 1991, 441-464. (https://stanford.edu/~alroth/sorority.html).