Ranking algorithm

[dodo2]

Almost all of the discussion regarding ranking is about ranking advanced or categorical programs on the primary list. Very little information is available regarding ranking prelim programs at the end of on primary and/or on the supplementary list.

Also, from ranking algorithm standpoint,

A. Does the order in which the applicants are processed have any impact on the match? if so, does it put you at a disadvantage to have supplementary lists?

B. If all the top programs are going after the same candidates and all top candidates are going after the same top programs, what effect would this have on the match?

C. If the top candidates are going after regional programs, what impact would this have on the match?

D. Is the algorithm and the software stable enough so that it would yield the same result if run multiple times?

E. Does it really favor applicants over programs? If so how?

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[dodo2]

BKN,
Do you know of any programs that have researched this algorithm? After all, the programs and applicant's future depends on it. All the interviewing and ranking does not mean a thing if the algorithm is not stable and/or is faulty. I don't want to sound alarmist but, all software has bugs in them. I just don't want a bug to screw me out of a career.

 

[Hurricane]

BKN,
Do you know of any programs that have researched this algorithm? After all, the programs and applicant's future depends on it. All the interviewing and ranking does not mean a thing if the algorithm is not stable and/or is faulty. I don't want to sound alarmist but, all software has bugs in them. I just don't want a bug to screw me out of a career.

Yeah, does the software run on Windows? If so, then I DEFINITELY don't trust it. Especially if they run it on a computer that has had a Sony music CD inserted into it during the last year.

Didn't something happen with one of the early matches last year? I vaguely remember hearing something about how they made a mistake and had to rerun the match program after they had already notified everyone of their match.

 

[daisyduke]

Yeah, that was the urology match.... but it is completely seperate from the NRMP.

 

[dodo2]

The problem is, there is no way for applicants or programs to know if the match screwed them up.

 

[(nicedream)]

Almost all of the discussion regarding ranking is about ranking advanced or categorical programs on the primary list. Very little information is available regarding ranking prelim programs at the end of on primary and/or on the supplementary list.

Also, from ranking algorithm standpoint,

A. Does the order in which the applicants are processed have any impact on the match? if so, does it put you at a disadvantage to have supplementary lists?

B. If all the top programs are going after the same candidates and all top candidates are going after the same top programs, what effect would this have on the match?

C. If the top candidates are going after regional programs, what impact would this have on the match?

D. Is the algorithm and the software stable enough so that it would yield the same result if run multiple times?

E. Does it really favor applicants over programs? If so how?

A. No - an applicant is matched to his/her highest possible program until another application is processed that exceeds it at that particular program - the previous one is then run again. This continues until all applicants possible are matched.

B. It has the effect of making those programs more competitive (which you would assume). Each program and each applicant can only have one applicant/program in each spot on their rank list. There will always be someone/some place ranked higher than the other all the way to #1. Top programs are likely to match top students and top students are likely to match at top programs thanks to this algorithm.

E. Yes, by running applicants' rank lists before programs'.

 

[dodo2]

Nicedream:

Your answers to A. E. are contradictory.

How can you say that the algorithm favors the applicants because it processes applicants before programs but the applicants who are processed first are not favored to those who are processed later.

 

[daisyduke]

The algorithm favors the applicant b/c all things being equal, the applicant's preference takes priority over the program's preference. For example, say you are the country's top applicant for internal medicine. If you rank Hopkins 1st and yale 2nd but Hopkins ranked you as #2 and Yale ranked you as #1, you still match at Hopkins (assuming Hopkins takes atleast 2 people for IM!!). If the algorithm favored the programs, you would match at Yale even though you ranked Hopkins #1 and they ranked you high enough to match there.

It makes no difference if your list is run first or mr. AOA smarty pants from California's list is run first.... if you are ranked higher on Hopkins' list than mr. smarty pants you will bump him down when your list is run and vice versa.

 

[dodo2]

I like your explanation. To understand this, let us work thru this example.

MY ROL
1.Hopkins
2. Yale

MR.AOA's ROL
1.Hopkins
2.Yale

Hopkins ROL , number of spots 2
1.AOA
2.DODO

Yale ROL number of spots 2
1.AOA
2.DODO

Process My ROL first

1.HOPKINS since HOPKINS has 1 spot open tentative match

PRocess AOA's ROL
1.Hopkins since HOPKINS has 1 spot open tetantive match

Yale has two unfilled positions
All matches are final
Both AOA and I get Hopkins

This scenario is unlikely since as # 1 program, they will have less number of spots than the applicants who want them

If Hopkins has only one position, AOA bumps me and I get Yale. Hopkins get want it wants (Mr. AOA) not me.

If Mr.AOA ranks Yale over Hopkins, He gets yale and I get hopkins. In this case both AOA and I get what we want and not Hopkins and Yale. Thus the algorithm favors applicants over programs.

 

[mosche]

This month's issue of The New Physician does an excellent job of explaining the whole process -- at least I thought that it was a good job.

 

[BigBadBix]

I think the detailed description & example on the NRMP site is very helpful.

 

[dodo2]

That NRMP Site example does not demonstarte how the process favors an applicant as opposed to a program. It also does not sufficiently explain the use of primary list and/or supplimentory lists for prlim programs. e.g. advantages and disadvantages of adding prelim programs at the end of primary list.

 

[mosche]

That NRMP Site example does not demonstarte how the process favors an applicant as opposed to a program. It also does not sufficiently explain the use of primary list and/or supplimentory lists for prlim programs. e.g. advantages and disadvantages of adding prelim programs at the end of primary list.

While I also think that the NRMP sight is good, I do believe that the article in the magazine does a much more comprehensive job.

 

[dodo2]

Can you please post a link to that mag. article.

 

[BigBadBix]

That NRMP Site example does not demonstarte how the process favors an applicant as opposed to a program. It also does not sufficiently explain the use of primary list and/or supplimentory lists for prlim programs. e.g. advantages and disadvantages of adding prelim programs at the end of primary list.

I am aware that the NRMP site doesn't address the prelim issue, but that was only one of several you brought up. In fact, you just devoted a lengthy post to trying to understand how the match algorithm works in favor of the applicant. I therefore brought up the NRMP explanation as it does, in fact, demonstrate clearly how the applicant is favored. The example on that site is similar to the one you came up with, except that it is more complex. The fact that you can't understand how that site answers your question is no reason to be rude to someone who is simply trying to be helpful. Now I wish I'd just told you to do a search - this topic has been discussed ad nauseum on SDN over the years.

 

[dodo2]

Uhh? I was not being rude to anybody. Save your ammunition for more worthy causes.

 

[mosche]

Can you please post a link to that mag. article.

You can google "The New Physician" and it will take you to the magazines website; however, at present the November edition is the one showing online. The article that I was referring to is the December 2005 article, and it's not yet online -- not that I could find anyway. I got the hard copy two days ago, so you might be able to get it at your med. school library. If I find a link, I will post it.

 

[dodo2]

Thanks mosche

 

[BKN]

BKN,
Do you know of any programs that have researched this algorithm? After all, the programs and applicant's future depends on it. All the interviewing and ranking does not mean a thing if the algorithm is not stable and/or is faulty. I don't want to sound alarmist but, all software has bugs in them. I just don't want a bug to screw me out of a career.

The others have answered the questions pretty well, I think other than the flaming. Just keep saying to yourself "I'll rank 'em the way that I want them."

 

[mosche]

Thanks mosche

You're welcome. I hope you were able to find it.

 

[jennyklm]

I like your explanation. To understand this, let us work thru this example.

MY ROL
1.Hopkins
2. Yale

MR.AOA's ROL
1.Hopkins
2.Yale

Hopkins ROL , number of spots 2
1.AOA
2.DODO

Yale ROL number of spots 2
1.AOA
2.DODO

Process My ROL first

1.HOPKINS since HOPKINS has 1 spot open tentative match

PRocess AOA's ROL
1.Hopkins since HOPKINS has 1 spot open tetantive match

Yale has two unfilled positions
All matches are final
Both AOA and I get Hopkins

This scenario is unlikely since as # 1 program, they will have less number of spots than the applicants who want them

If Hopkins has only one position, AOA bumps me and I get Yale. Hopkins get want it wants (Mr. AOA) not me.

If Mr.AOA ranks Yale over Hopkins, He gets yale and I get hopkins. In this case both AOA and I get what we want and not Hopkins and Yale. Thus the algorithm favors applicants over programs.

So it sounds like if you ranked a program #2 or #3, a top-ranked, highly desirable program could fill up before the algorithm gets to you if you don't match at your top choice. Is this correct?

 

[BigBadBix]

So it sounds like if you ranked a program #2 or #3, a top-ranked, highly desirable program could fill up before the algorithm gets to you if you don't match at your top choice. Is this correct?

It sounds like you are thinking that the algorithm gives every person their 1st choice, then every person their 2nd choice, etc. This is actually not how it works. Instead, each applicant is tentatively placed at the program highest on their list that also ranked them, with the possibility of being kicked off the list if too many applicants that are higher on that program's list also want to go there. Even if you are the last applicant to be matched by the algorithm, you can kick others off of a program's list if the program wants you badly enough. Thus, all that matters is (1) the order of your list, and (2) how high you are on each program's list.

In your hypothetical situation, if you didn't match at #1, it would try to put you in #2. If #2 was full, anyone who had already been tentatively matched there but was ranked lower than you on the program's list would then get knocked out. The algorithm would then try to match them at the next place on their rank list. On the other hand, if you were ranked lower than those already filling program #2's list, the algorithm would not match you there and go to #3, etc.

Am I making any sense? I think it's easier to see by looking at examples - when it's written out in words it looks more confusing than it is (at least to me).

 

[jennyklm]

It sounds like you are thinking that the algorithm gives every person their 1st choice, then every person their 2nd choice, etc. This is actually not how it works. Instead, each applicant is tentatively placed at the program highest on their list that also ranked them, with the possibility of being kicked off the list if too many applicants that are higher on that program's list also want to go there. Even if you are the last applicant to be matched by the algorithm, you can kick others off of a program's list if the program wants you badly enough. Thus, all that matters is (1) the order of your list, and (2) how high you are on each program's list.

In your hypothetical situation, if you didn't match at #1, it would try to put you in #2. If #2 was full, anyone who had already been tentatively matched there but was ranked lower than you on the program's list would then get knocked out. The algorithm would then try to match them at the next place on their rank list. On the other hand, if you were ranked lower than those already filling program #2's list, the algorithm would not match you there and go to #3, etc.

Am I making any sense? I think it's easier to see by looking at examples - when it's written out in words it looks more confusing than it is (at least to me).

sort of... but if I were ranked higher than the other folks tentatively matched, would it still be possible to kick others off if they all ranked it #1? wouldn't they be losing their first choice in favor me who ranked it #2?

 

[G-Man]

sort of... but if I were ranked higher than the other folks tentatively matched, would it still be possible to kick others off if they all ranked it #1? wouldn't they be losing their first choice in favor me who ranked it #2?

Very good question. What if I do not tent. match into my first 3 choices and my 4th ranked me #1 but is allready filled with applicants who ranked it 1st on their list, then what?

 

[fantasty]

It doesn't matter whether the person you bumped ranked it #1 even if you ranked it #4. If you are higher on the programs list, you'll bump them and then they have to go to their #2.

 

[SergeGainsbourg]

Why would a program worry about whether a candidate they want is going to rank them highly? When the algarithm spins wouldn't it all work out the same for them too if they just rank candidates according to their actual preferences.

 

[DrDre']

Serge,
Love the name! Wish I had been married to as many beautiful women as you!
Bonne chance en Mars!

 

[jeffsleepy]

If you want something rigorous, the match uses a variation of the stable marriage algorithm which I'm sure you can google up. And yes, in such an algorithm, the ones doing the proposing (applicants) are favored over the ones doing the accepting/rejecting (programs).

 

[FACS]

If you want something rigorous, the match uses a variation of the stable marriage algorithm which I'm sure you can google up. And yes, in such an algorithm, the ones doing the proposing (applicants) are favored over the ones doing the accepting/rejecting (programs).

worthless post.


Yes, this one is no better.

 

[dodo2]

Serge:
What you say makes perfect sense and is logical. However, just like the applicants worry about whether they are going to match and to which program; the PDs worry about who are they going to get and if they will have unfilled positions.....Humans!

 

[robotsonic]

Why would a program worry about whether a candidate they want is going to rank them highly? When the algarithm spins wouldn't it all work out the same for them too if they just rank candidates according to their actual preferences.

I wondered about this also. I think the answer is that programs like to brag that they were able to fill x number of spots without going below x + y on their rank list. So if their list is filled with awesome candidates who don't act interested in actually coming, the program has to go very far down on its rank list and looks bad the next year.

That's my guess anyway. Otherwise, you are right, the programs are better off ranking in order of preference.

 

[jeffsleepy]

worthless post.


Yes, this one is no better.

How is it worthless? Dodo2 wanted to know whether any research was done on this algorithm and I stated where that information could be found. I only know the basics of how it works so I couldn't give any details.