clock menu more-arrow no yes

Filed under:

Avoiding the Gambler's Fallacy with the Astros

New, 7 comments

My favorite book that I've read in the last year is The Drunkard's Walk.  It's essentially a history/explantion about how mathematicians have tried to observe and measure tendencies in our lives with statistics.  The discussion that I particuallarly enjoyed was the discussion of the Gambler's Fallacy because, as Amos and Tversky first discovered, humans aren't wired to intuit what the law of averages really gets at—that short run streaks don't change the balance of long run probabilities (I hope I did that justice).

So I was particularly excited when BtB suggested a way to put this concept use in the early part of the season.

Sky provided a spread sheet that allowed you to input your team's original projection total from your projection source and then the actual record.  It then spits out the newly expected win total for the season taking into account the true talent level and the available sample space.

Here's what happend when I used the Community Projection Project:

pW pL aW aL nW nL delta
Astros 83 79 4 8 80.9 81.1 -2.1

p=predicted, a=actual, n=new prediction

The caveat I'd like to bring to the idea of trying to account for the Gambler's fallacy is that the Astros offense, by it's very construction, is itself streaky.  So while there might not be predictive power in a short run streak, I'm not sure the fallacy entirely applicable in our case, but maybe someone with a better understanding of the concept can chime in.