Um, so when Nate Silver tells us he’s calculated odds of 2 in 3 that Republicans will control the house after the election, this number should be discarded as noise because it’s a common-sense belief that the Republicans will gain that many seats?
No, of course I didn’t mean anything like that. Here is how I see this situation. Silver has a model, which is ultimately a piece of mathematics telling us that some p=0.667, and for reasons of common sense, Silver believes (assuming he’s being upfront with all this) that this model closely approximates reality in such a way that p can be interpreted, with reasonable accuracy, as the probability of Republicans winning a House majority this November.
Now, when you ask someone which party is likely to win this election, this person’s brain will activate some algorithm that will produce an answer along with some rough level of confidence. Someone completely ignorant about politics might answer that he has no idea, and cannot say anything with any certainty. Other people will predict different results with varying (informally expressed) confidence. Silver himself, or someone else who agrees with his model, might reply that the best answer is whatever the model says (i.e. Republicans win with p=0.667), since it is completely superior to the opaque common-sense algorithms used by the brains of non-mathy political analysts. Others will have greater or lesser confidence in the accuracy of the model, and might take its results into account, with varying weight, alongside other common-sense considerations.
Ultimately, the status of this number depends on the relation between Silver’s model and reality. If you believe that the model is a vast improvement over any informal common-sense considerations in predicting election results, just like Newton’s theory is a vast improvement over any common-sense considerations in predicting the motions of planets, then we’re not talking about a common-sense conclusion any more. On the other hand, if you believe that the model is completely out of touch with reality, then you would discard its result as noise. Finally, if you believe that it’s somewhat accurate, but still not reliably superior to common sense, you might revise its conclusion using common sense.
What you believe about Silver’s model, however, is still ultimately a matter of common-sense judgment, and unless you think that you have a model so good that it should be used in a shut-up-and-calculate way, your ultimate best prediction of the election results won’t come with any numerical probabilities, merely a vague feeling of how confident you are.
What you believe about Silver’s model, however, is still ultimately a matter of common-sense judgment, and unless you think that you have a model so good that it should be used in a shut-up-and-calculate way, your ultimate best prediction of the election results won’t come with any numerical probabilities, merely a vague feeling of how confident you are.
Um, so when Nate Silver tells us he’s calculated odds of 2 in 3 that Republicans will control the house after the election, this number should be discarded as noise because it’s a common-sense belief that the Republicans will gain that many seats?
Boy did I hit a hornets’ nest with this one!
No, of course I didn’t mean anything like that. Here is how I see this situation. Silver has a model, which is ultimately a piece of mathematics telling us that some p=0.667, and for reasons of common sense, Silver believes (assuming he’s being upfront with all this) that this model closely approximates reality in such a way that p can be interpreted, with reasonable accuracy, as the probability of Republicans winning a House majority this November.
Now, when you ask someone which party is likely to win this election, this person’s brain will activate some algorithm that will produce an answer along with some rough level of confidence. Someone completely ignorant about politics might answer that he has no idea, and cannot say anything with any certainty. Other people will predict different results with varying (informally expressed) confidence. Silver himself, or someone else who agrees with his model, might reply that the best answer is whatever the model says (i.e. Republicans win with p=0.667), since it is completely superior to the opaque common-sense algorithms used by the brains of non-mathy political analysts. Others will have greater or lesser confidence in the accuracy of the model, and might take its results into account, with varying weight, alongside other common-sense considerations.
Ultimately, the status of this number depends on the relation between Silver’s model and reality. If you believe that the model is a vast improvement over any informal common-sense considerations in predicting election results, just like Newton’s theory is a vast improvement over any common-sense considerations in predicting the motions of planets, then we’re not talking about a common-sense conclusion any more. On the other hand, if you believe that the model is completely out of touch with reality, then you would discard its result as noise. Finally, if you believe that it’s somewhat accurate, but still not reliably superior to common sense, you might revise its conclusion using common sense.
What you believe about Silver’s model, however, is still ultimately a matter of common-sense judgment, and unless you think that you have a model so good that it should be used in a shut-up-and-calculate way, your ultimate best prediction of the election results won’t come with any numerical probabilities, merely a vague feeling of how confident you are.
Want to make a bet on that?