The Match Algorithm – How Does it Work?

Understanding the Match Algorithm

The Match algorithm is based on the work of Alvin Roth and Lloyd Shapely – who jointly won the 2012 Economic Sciences Nobel. It is essentially a simple database which takes a list of residencies and a much larger list of hopeful medical students, and matches up their rank lists like a dating game show to determine the future residency of thousands of people every year. In How Long Does the Residency Match Algorithm Take To Run?Vishnu Ravi breaks it down in an easy to understand format. I love that he took the time to actually create a database of applicants and programs, using the number of each from the 2014 Match, to accurately measure the process and ran the code 100 times.

His results? It takes an average of 17 seconds.

Yes, 17 seconds.

Then Why The Wait?!

So why is there a month between submission of Rank Order Lists and The Match? Administrative tasks and data checking. On the ACGME side individual reports are generated for applicants, program directors and medical schools. One interesting bit of information I learned this year is that every residency gets a report with a list of the applicants they ranked, and where they actually matched. Some students will receive contacts from programs after the Match requesting participation in post-Match surveys in order to determine why those applicants didn’t rank them higher and get feedback on improving their interview process.

So, when is The Match?

There’s actually two Matches each year: the NRMP Match for ACGME residencies and the NMS Match for  AOA residencies. Both versions of the Match algorithm currently use the applicant list first, which means a student’s preference is considered before the residency program.

• The AOA/NMS Match comes first, with rank order lists due in late January and Match results in late February
  • As far as I know DO schools do not hold Match Day ceremonies, probably because un-matched students enter the Scramble that same day
• The ACGME/NRMP Match has ROL due in February with results in late March
  • Monday students find out if they matched
  • Un-matched students have Monday through Thursday to participate in the SOAP
  • Everyone finds out where they Matched on Friday (and many MD schools have ceremonies to celebrate this)

For the DO students

We’re currently working on an article for osteopathic students trying to decide which Match to take part in, so let us know any specific questions you might have in the comments! For my nerdy compatriots, especially former programmers, get more info via the resources listed below.

Resources:

• A Harvard presentation breaking down the algorithm in further detail
• Feeling Nerdy? Take a free course on algorithms from Princeton via Coursera (then solve the programming problem yourself)
• The AOA Match Description and 4 Common Myths
• The ACGME Match Description and Explanation of Delay in Results
• In the mood for a 2-minute video explanation? NRMP has one. And so does NMS.
• Vishnu Ravi has several interesting medically related projects on his site, check him out.
• 2012 Nobel Prize Economic Science summary