Stats Behind the Draft Lottery

J15

Registered User
Mar 18, 2009
1,057
305
Hope I've found the correct forum for this post but I had a few questions about how to interpret the draft lottery odds that are published by the NHL. This started because I decided to try and build my own lottery simulator, but now it's more a matter of curiosity. The team which finishes last has the following odds for the draft lottery.

1 OA - 18.5%
2 OA - 16.5%
3 OA - 14.4%

The lottery for 1 OA is pretty straight forward, but it's unclear to me exactly how odds are determined after this. From what I can gather online, it seems like these that these odds represent the marginal probability for the team picking at each position. This would mean given an infinite amount of simulations the last place team would actually pick 1st in 18.5% of the time, pick second 16.5% of the time, etc. This would mean that team X having a 16.5% chance of picking 2 OA implies the following equation must be satisfied

16.5% = P(team X picks second | team 1 picked first)*P(team 1 picked first) + ... + P(team X picks second | team N picked first)*P(team N picked first)

While this provides a constraint on the set conditionals, P(team X picks second | team i picked first) , it doesn't uniquely determine them. As far as I can tell, it's also not trivial to come up with a method of generating these conditionals.

For example a trivial way of generating a given conditional P(team X picks second | team i picked first) would be to just re-normalize all the odds to account for the team that picked first.

P(team X picks second | team i picked first) = P(team X picks second) / (1 - P(team i picks second))

While this method is simple, the conditionals generated won't satisfy the constraint for the total marginal probability. I was wondering if anyone knew exactly how these odds are determined?
 

Brodeur

Registered User
Feb 27, 2002
26,092
15,723
San Diego
If I were writing a program, you probably wouldn't have to worry about the residual odds other than first pick. Basically set up a random number generator to spit out something in the range of 1-1000 and set up a series of if statements to split up the odds accordingly. You'd just need to run the number generator three times and set up conditions if the winning team(s) were drawn again.

I think you're on the right track for the 16.5% calculation, it's just the sum of the scenarios where that team ends up with the 2nd pick.

lotto.jpg


If the 2nd place team wins (13.5% chance), the 1st place team would have 185 of the remaining 865 winning combinations (21.387%). The chance of that all happening is .135*.21387 ~ .02887.
 

WingsMJN2965

Registered User
Oct 13, 2017
18,106
17,699
I think this was the best system the NHL has had anyways

Seeing as Detroit would pick first or second, me too. :laugh:

I think the problem is they tried to fix one problem by blowing the solution way out of proportion. They could've prevented another Edmonton by simply banning teams winning the lotto more than once in say, three years.
 

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