Polls are not independent. If poll A is out by a large amount, then it's much more likely that poll B is also out.
That's a bias issue - I was only addressing sampling variation. If you wnat your model to address bias as well, of course you can build that in, given some priors on what the distribution of the bias is likely to be. I didn't bother in my model (which is why I was forecasting 98-99% chance of an Obama victory).
We could discuss potential poll bias as well, but I thought that was a bit too much for this short comment.
That's a bias issue - I was only addressing sampling variation. If you wnat your model to address bias as well, of course you can build that in, given some priors on what the distribution of the bias is likely to be. I didn't bother in my model (which is why I was forecasting 98-99% chance of an Obama victory).
We could discuss potential poll bias as well, but I thought that was a bit too much for this short comment.