How The Sisterhood Rush Is A Matching Market

By Wailin Wong | NPR
Friday, October 7, 2022

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Sisterhood Rush. It’s a college tradition full of excitement and anxiety for recruits. For economists, it illustrates a concept that plays a huge role in our economy: market matching.



As of now, the sorority rush has ended on college campuses across the country. This is the time of year when sororities recruit new members. And it also illustrates an important economic concept – market matching. Wailin Wong and Adrian Ma of our daily economics podcast The Indicator explain.

WAILIN WONG, BYLINE: You may have heard of the Sorority Rush because it’s been a big hit on TikTok for the past two years. And it’s this busy week of parties and other events.


UNIDENTIFIED PERSON: Hi, all of you. So today is the first round of the fraternity. And I’m so excited because we can wear our cute little dresses.

ADRIAN MA, BYLINE: #RushTok started with sorority women at the University of Alabama. They were posting behind the scenes videos and all of their daily outfits…


UNIDENTIFIED PERSON: My shoes are from TJ Maxx.

MA: …to the songs and rituals that take place during the week.


UNIDENTIFIED GROUP: PI, PI, Phi, Phi, Phi, P for Phi for Beta Phi…

WONG: The TikTok posts gave some insight into this particular aspect of campus culture. And they inspired discussions about social hierarchies and elitism and the role of the Greek system in university life. But you know, what we haven’t talked about is the economy.

MA: And that’s where we come in because it turns out that the sorority rush exemplifies a concept called matching markets. And the corresponding markets are extremely important for the economy. Al Roth is a professor of economics at Stanford.

WONG: If you go to a cocktail party and someone asks you, Professor Roth, what do you do for a living? – and you say, well, I pioneered market matching research, and someone says, well, what is that? – What are you saying?

AL ROTH: Well, it happened to me more than once. And I normally start by saying what it is not.

MA: What matching markets are not, they are markets where prices are involved. This is called commodity markets.

ROTH: Commodity markets are markets where you don’t care who you trade because commodities are all the same. And so, what the market is supposed to do is find the price at which supply will equal demand. But in many markets, we don’t deal in commodities. You care who you deal with. There is a relationship involved. And these are corresponding markets.

WONG: The labor market is an example of a matching market; the same goes for online dating and the residency matching process for medical students and hospitals.

MA: Al had the idea to investigate the sororities of his undergraduate students who were involved in the Greek system. The sororities were particularly intriguing because they had a centralized clearinghouse for making matches. Al wanted to know how the process worked and whether it produced what economists call stable correspondences.

ROTH: A match is stable if there are no what we call blocking pairs. And a blocking pair is a pair of people who are unmatched and both would prefer to be matched.

WONG: So let’s just say I’m doing sorority rush and I like House Alpha the best. So I rank Alpha house #1 and place Beta house at #2. Now Alpha house puts a group of other students ahead of me on their list, but Beta house puts me at the top of their rankings. The system will match me with House Beta because it’s the highest house on my list that also ranked me high. It’s a stable game.

ROTH: It’s the best you can get considering what’s out there and what everyone else is getting.

WONG: So if you look at the medical residency game, organ donation, high school admissions — those are all pretty high-stakes situations where Al’s work in the corresponding markets played a big role. The sororities don’t get as much attention, even though their matching process works largely the same.

ROTH: Sometimes people are surprised that economists study things like this. But economists study how scarce resources are allocated and how to make them less scarce, so it is all about allocating scarce resources in a two-sided market.

MA: Maybe the next episode of RushTok will focus on economy rather than outfits?

WONG: Wailin Wong.

MA: Adrian Ma.

WONG: NPR News. Transcript provided by NPR, Copyright NPR.

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