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No, it didn't predict individual behaviour, but it tried to predict a global outcome, which is based on the summation of 22 (plus subs) individual behaviours/ac

No, it didn't predict individual behaviour, but it tried to predict a global outcome, which is based on the summation of 22 (plus subs) individual behaviours/actions. And that what made it fail in this specific case.

alttab 12y ago
Statistics is used when a more accurate model cannot be found. This essentially assumes that there are a lot of unmeasured variables. So yes, statistically this was accounted for.
ajross 12y ago
Can you rephrase that in a way that makes sense? You appear to be saying that because sports teams are small that no probabilities can be assigned to the results of their games. There's literally a whole gambling industry that exists precisely because such a thing is possible. Likewise you appear to be arguing against insurance as a business model. My guess is that you're misinterpreting Silver's work and assuming he was "predicting" that Brazil "would" win. He wasn't, and didn't claim to. He said Brazil was more likely to win, and gave numbers to that effect (that in this case happened to be wildly wrong).
- peter-row 12y ago
  I think he's saying it's a souped-up poisson model, not an agent based model. It's not trying to predict individual behavior. A poisson model is probably valid, but it should perhaps be refined a bit. Maybe it should account for a systematic drift if the whole team plays badly (or a vital player, like the goal keeper, has a bad day). But it's probably really hard to calibrate that, and it's probably not too relevant unless you want to model major upsets.
  - gbhn 12y ago
    Wouldn't that refinement basically be identifying the tails as quite a bit fatter than you'd thought before? But in that case, the tails are probably substantially fatter for everyone, and so the numbers 538 is quoting may not be far from the "real" ones. My reading of this 538 World Cup analysis is that the error bars are taken as being very large, and the relative numbers are mostly interesting as a means of comparing the impacts of various players and other factors in the model. Obviously there can still be major flaws in this method, chief among them being that the method tends to atomize the team's contributions. But that's not a horrible first pass, and still can yield some interesting insights.
    - peter-row 12y ago
      Yes and yes. It's still probably the biggest upset ever, but not as unlikely as their model suggests.

alttab 12y ago

Statistics is used when a more accurate model cannot be found. This essentially assumes that there are a lot of unmeasured variables. So yes, statistically this was accounted for.

ajross 12y ago

Can you rephrase that in a way that makes sense? You appear to be saying that because sports teams are small that no probabilities can be assigned to the results of their games. There's literally a whole gambling industry that exists precisely because such a thing is possible. Likewise you appear to be arguing against insurance as a business model. My guess is that you're misinterpreting Silver's work and assuming he was "predicting" that Brazil "would" win. He wasn't, and didn't claim to. He said Brazil was more likely to win, and gave numbers to that effect (that in this case happened to be wildly wrong).

peter-row 12y ago
I think he's saying it's a souped-up poisson model, not an agent based model. It's not trying to predict individual behavior. A poisson model is probably valid, but it should perhaps be refined a bit. Maybe it should account for a systematic drift if the whole team plays badly (or a vital player, like the goal keeper, has a bad day). But it's probably really hard to calibrate that, and it's probably not too relevant unless you want to model major upsets.
- gbhn 12y ago
  Wouldn't that refinement basically be identifying the tails as quite a bit fatter than you'd thought before? But in that case, the tails are probably substantially fatter for everyone, and so the numbers 538 is quoting may not be far from the "real" ones. My reading of this 538 World Cup analysis is that the error bars are taken as being very large, and the relative numbers are mostly interesting as a means of comparing the impacts of various players and other factors in the model. Obviously there can still be major flaws in this method, chief among them being that the method tends to atomize the team's contributions. But that's not a horrible first pass, and still can yield some interesting insights.
  - peter-row 12y ago
    Yes and yes. It's still probably the biggest upset ever, but not as unlikely as their model suggests.