arod Unregistered User (6/7/00 5:53:13 pm) Reply Ranking Backups I have been asking around (w/o much success) about how exactly the match algorithm works. If I have a strong indication that my home institution wants me and I choose to use this as a backup where should I put them in the rank list? If they rank me high and I rank them let's say 9 or 10 is there any way I will get screwed and not match? Any input on the strategy of ranking a backup would be appreciated. Good Luck to all Kent Unregistered User (6/7/00 7:41:22 pm) Reply Matching algorithm Nobody understands this beast! Actually, it's been well written about and has been used since the 1950s. The nuts and bolts are that you submit a rank list of the places you would like to go and the programs submit a rank list of the people they want. The computer matches the lists as best it can, that is, the programs get their best picks and the candidates get their best picks, too. The basic strategy is two-fold--applicants accept positions UP their list and programs accept applicants DOWN their list. Here's how it works. In the first round, the programs can offer the same number of positions (for example, the University of Minnesota has six orthopaedic residents) that they have in their resident class. MN can make six offers to the six top candidates on their list. Some of the spots will fill, say two of 'em, with people who were top ranked with MN and ranked MN at the top of their list. There can't be a better fit that, so those spots are out of the match. The other four spots will be offered DOWN Minnesota's list until they get filled. It doesn't matter if your list is one of the first run or one of the last. You can't be beat out by a lower ranked candidate. So some of the people occupying those tentative match spots will be down MN's list until they get to your list. Say you're ranked highly by MN and you've got them high on your list. You'll be placed tenatively in one of MN's spots and the process continues until the class is filled with the most desired candidates that ranked that program. If someone comes along that's more desired by MN than you, and they also ranked MN highly, they'll knock you down the list. If three other people are more desired by MN and ranked MN highly, they too will knock you down and off the list (remember, two of the spots were "perfect" matches, i.e., the two top candidates that MN wants and who want to go to MN). So now you got knocked off MN's list (you won't match there), because the program is tenatively filled with more desirable candidates (some of whom will get replaced if a more desirable candidate comes along). So the algorithm looks at your next choice, e.g., Pittsburgh. But, alas, Pitt didn't even rank you! You can't match there, so it looks at your third choice, e.g., Duke. Duke has you one their list, but your not one of their top picks. If there are open spots, i.e., the spots are not filled by more desirable candiates, you tentatively match at Duke until you get moved down and off the list or the Match runs fully and you're still on Duke's list. In the case of the latter, you've matched at Duke. This process of checking perople's rank lists and looking to see if they are ranked at that program (and if they are more desired by that program) continues until everyone is placed with their highest choice that also wanted them, or the spots are all filled and you're one of the unlucky unmatched candidates. There are two basic strategies for organizing your rank list. 1. Rank ALL acceptable programs. Orthopaedics, unlike Internal Medicine, doesn't really allow the option of not ranking programs. Don't rank a program if you absolutely wouldn't want to go there. 2. Rank the programs in order of YOUR preference. So, if you've got a couple of dream programs that you'd be thrilled to go to (but maybe don't have the greatest chance), then rank them at the top of your list. You never know what might just shake out. If your home program is a sure bet and you want to go there, then rank them first. If your home program (or a few others) are sure bets but you really would like one of those dream programs, then rank them at the bottom of your list. Remember, you go UP the list. So if they run the match list of your home program (a sure bet) and it's at the bottom of your list, you can only do better (never worse). If they run the match list of your home program (the sure bet), and you rank it No. 1, you'll go there because you can't get a better fit between the two lists. Say you rank the sure thing at the bottom of the list, they run Sure Bet U's match list, you're on it and they're on your list, you'll be tenatively matched there. Then when they run some of the other programs that you ranked higher than Sure Bet U, you'll be tenatively matched at one of those programs and taken off Sure Bet's list. You'll keep moving up YOUR list as long as there is an open spot at those more desired programs (they offer spots DOWN their list) and you are more desired than one of the candidates at that program. If these more desired programs are tenatively filled with more desired candidates than you, you can't take a spot away from those people and you'll end up at Sure Bet. If Sure Bet U wasn't such a sure bet (you aren't top ranked like you thought and the other programs either didn't rank you, or you're so far down their lists), you could be knocked off Sure Bet's list by more desired people. Since there's no place to go down your list, you won't match. Man, this is a pain to explain. Quick and dirty--1. Rank all acceptable programs. 2. Rank them in the order of YOUR preference (really want to go to Duke, but don't think you've got much of a chance, then rank them No. 1 or want to go to your home program and they'll almost surely take you, then rank them No. 1) 3. Sure bets (if you're sure about them) can safely go at the bottom. 4. You accept offers UP your list. 5. Programs make offers DOWN their list. 6. You can never replace a more desired candidate (you're lower ranked) and, in turn, you can't be replaced by someone lower ranked than you. 7. The supposed end result is that the programs get the highest ranked candidates and candidates get their highest choice. Sure hope this rambling exlanation makes a little sense. slk Local user (6/8/00 8:28:35 am) Reply Re: Matching algorithm Thanks a lot kent, that was a big help. Let me ask you one point of clarification. So if you can never get bumped off a program's rank list by someone ranked lower than you, does this mean: Say a program ranks me 5 on their list, and I rank them at the bottom of my list, say 15. Someone else is ranked by the program #6, one below me, but they rank the program No. 1 on their list. Won't that other person be a much better "match" overall, even though they are ranked a little lower by the program? Bob Local user (6/8/00 9:39:46 am) Reply Re: Matching algorithm A good question. If you were to rank a program No. 15 (let's say Mayo) and that program ranks you high, let's say #4, then you would get that spot if you didn't match at one of your higher 14 choices. This holds true even if a student who ranked Mayo as their top spot and Mayo were to rank them behind you a little bit (say #6). Although it seems that the other candidate has a better "match", the advantage goes to the student who is ranked higher on the program's list. I hope that makes sense. The bottom line is this... when making out your rank list, put the programs in the order that you would be happiest, and things will work themselves out. Don't try to figure out which programs will be ranking you where on their list. Kent Unregistered User (6/8/00 1:22:35 pm) Reply Paging Dr. Al Gorithm I think Bob's correct, although I'm far from an expert on this matter. See if you can find some of the articles written about the algorithm. Let's look at your case. If you are ranked within the number of spots offfered by the program (say MN has six spots and you're ranked either 6th, 5th, 4th, 3rd, 2nd, or 1st), and you have that program ranked first, then it's generally a lock that you will go there (you might get picked off by your second program that had you ranked something like 1st or 2nd). If you are one of the top six at MN, but you ranked MN last, it would depend on the order in which MN list is run. If MN is one of the first lists run and you're a top-six pick, then you'll be tenatively placed there. Notice I said "tenative". As they get to the other rank lists, you might appear sufficiently high on one of your higher ranked program's (say Mayo) list to get moved UP to that program. So, MN would be the worst you could do. This is why I said that you accept spots UP your list and programs offer spots DOWN their list. It would seem that you're guaranteed a match somewhere as long as you're one of the candidates ranked within the total number of the resident class, i.e., six or better at MN, ten or better at Mayo and Harvard, eight or better at Pittsburgh, etc., etc.). It also would seem to make sense that unmatched students fall in one of two categories: 1. They weren't ranked by ANY program, so there can't be a match, or 2. They were ranked, but pretty far down the list (say the algorithm ran their rank list early on, Mayo's ranked No. 1 and Mayo hadn't tenatively filled with more desired students. This student is ranked something like 35 on Mayo's list, so there are lots of more desired students to fill a class of 10. Well, that guy or gal will tenatively occupy a spot until another, more desired applicant's rank list is run and the latter will move the low-ranked person down a spot or off Mayo's list. Once off Mayo's list, the algorithm looks at the applicant's next choice and sees if the student can be tenatively placed. If that program has more desired candidates in the spots, then it's down to the third choice. Maybe the student can be tenatively placed, but along comes a more desired person, and the lower ranked applicant gets bumped. If this process continues all the way down this person's rank list (thereby exhausting the list), there aren't any programs left and the applicant is unmatched. This is what I meant by not worrying about whose rank list gets run first. You can't be replaced by somebody lower ranked than you and you can't replace anybody higher ranked. Remember those two simple principles: 1. Rank ALL acceptable programs and 2. Order your rank list according to YOUR preference, not how you think programs will rank you. =================================