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Oct 312009
 

If you play office pools using some of the largest online pool websites — ESPN, Yahoo, UPICKEM, etc. — you can see the percentages of other users’ picks for every team. If you take a look at them, you’ll notice they’re remarkably similar. But how do you use this information? Here’s how: it is a decent initial approximation for the percentages of picks in your own local pool.

Let’s say 10% of all users on ESPN picked Cleveland, and you play in a pool with 15 participants. Using the ESPN distribution estimate, that means you can expect 1.5 of your participants picks Cleveland.

But it can’t be 1.5. It could be 1 or 2. It could also be 0, 3, 4, or 5, or more if you’re playing in a pool of Cleveland fans. Given the ESPN probability p, where p=10%, the formula for estimating the probability in an N-participant pool that a certain number i picked a team is:

Combin(N,i)*p^i*(1-p)^(Ni)

Enter that formula in Excel, substitute the is and you can see the probabilities that the number of your friends who picked Cleveland are:

0 21%
1 34%
2 27%
3 13%
4 4%
5 1%

If you’re not considering this for every game every week, you’re short-changing your office pool picks.

 Posted by on October 31, 2009 at 11:25 am