Error in Harrington?

Hi, YohanN7

I will move your thread to tournaments discussion forum where it belongs.

Best regards,

Kurrkabin

Hi YohanN7,

I can verify that your calculation is correct.
Please find attached calculation:

3rd collumn easily calculates the % on getting 1st place - no worries there

4th and 5th collumn calculate that if A gets first, X gets 2nd.
The same for B,C and D
Still we reach the same numbers as Harrington.

Now I calculated the probability that A gets 3rd.
This happens on 6 different "occurences", I named all 6 of them.
Now I took the numbers from X getting 1st and put them in one collumn.
Furthermore from the previous calculations I took the probabilities that the 2nd place goes to X when Y gets 1st (so from the overall 2nd calculations)
The third place is then simply calculated for "B gets 1st,C gets 2nd,A 3rd" with the chips of A and D => 5000/(1500+5000)
==>all lines have to be multiplied with probability of getting 1st and 2nd in the line. All the results added up give 21.5043% of getting 3rd for Player A

So harrington was wrong, your calculation correct.
(I estimated that the calculations for all others would be hopefully the same result,too)

Gratulations!

Hey Jonah,

Assuming that the calculations are based on ICM your results are indeed correct. (you can double check here http://www.icmpoker.com/Calculator.aspx ) Or in Sven's detailed post

If this is not an error in Harringtons book, my guess is that his method of equity modelling was somewhat different from ICM, but i'm not sure what that would be, maybe it's in the book somewherre (i don't have it with me). But given that the first two places are the same it's likely just an error because using a different model (ex. malmuth-weitzman) would result in different numbers for all places.

Cheers,
FF

Thank you very much for your answers SvenBe and FishermansFriend. SvenBe, your post is wonderfully detailed, and I can use it to double check the numbers in a document I've produced alongside with my code implementation of the ICM formula.

Yes, the formula is intended to be the ICM formula, and I'm pretty sure Harrington describes ICM in the surrounding text, tough he doesn't explictly say ICM.

While I'm at it: My implementation now works nicely and produces the correct numbers (I am fairly sure by now), but there are interesting theoretical problems associated with it. Performance, for instance, is an issue for many players and, especially, many prizes paid.

One can probably use previously calculated numbers (e.g first place probabilities) when calculating deeper down (e.g second place probabilitis). (SvenBe's post indicates this too). Thus it will in the end be memory vs CPU. As it stands now I loop through everything and store nothing. I have a recursive version too which (while very elegant) performs like the loop version.

The interested nerd can find a recursive code snippet here:
http://www.holdemresources.net/hr/sngs/icm/icmjava.html
That is Java, but is easily translated to any language where recursion is fine. I use C++ myself from old habits.

/Johan =