I think there's a minor error in the analogy of "state results" to "coin flip".
In the coin flip scenario each throw of the biased coins are independent. How one lands does not effect the other. The same is likely not true for how states end-up voting.
This doesn't entirely invalidate your point (yes, if you "re-ran" the election repeatedly and he "nailed it" everytime we might conclude his probabilities were incorrect), but it does explain why if 10 "60% Obaba" states vote we might not necessarily expect 6 of them to come up for Obama...
> In the coin flip scenario each throw of the biased coins are independent. How one lands does not effect the other. The same is likely not true for how states end-up voting.
For sure. If I have a point, it's that there's not enough information in any election to claim that he "nailed it." Since the outcome he said was most likely seems to have occurred, it definitely supports his model and his approach. But you'd need to see a longer track record than exists to be sure. (think of each coin flip as being a separate national election).
Independence is a little bit of a red herring, though. There are LLNs and CLTs that allow for weak dependence between the observations, and any strong/systematic dependence between the states belongs in the model (and I think is in Silver's model, but I could be misremembering). And we would expect that 6 of 10 "60% Obama" states would come up for Obama. The interdependence is going to affect the variance but not the mean. So we should expect to see (say) 8 or more of 10 going to Obama happen more frequently than a naive binomial(.6, 10) distribution would predict.
In the coin flip scenario each throw of the biased coins are independent. How one lands does not effect the other. The same is likely not true for how states end-up voting.
This doesn't entirely invalidate your point (yes, if you "re-ran" the election repeatedly and he "nailed it" everytime we might conclude his probabilities were incorrect), but it does explain why if 10 "60% Obaba" states vote we might not necessarily expect 6 of them to come up for Obama...