Nate Silver's take on the Bloomberg Poll
Some of the accounts that I read about the Bloomberg poll avoided that trap, describing it as an “outlier.” I don’t have any huge problem with using that term, although that still leaves you with a choice to make.
1) You could just disregard the poll entirely, or,
2) You could include it in some sort of average and then get on with your life.
My general view, as I’ve expressed before, is that you should not throw out data without a good reason. If cherry-picking the two or three data points that you like the most is a sin of the first order, disregarding the two or three data points that you like the least will lead to many of the same problems.
At the same time, it’s important to take data in context. Many polls consistently show a partisan lean toward one or another candidate. And some polls just aren’t very good, taking shortcut after shortcut that leave them far short of taking a true random sample of voters.
The FiveThirtyEight forecast model seeks to strike a balance between these ideas. If it can place a poll into context based on what it knows about the polling firm, it will use it, although the model includes a lot of checks-and-balances that are supposed to prevent the model from overreacting to any one data point.
In this case, the firm conducting the Bloomberg poll (Selzer & Company) actually has a good track record, and their previous polls this cycle had not shown especially favorable results to Mr. Obama. So the model uses the poll, just carefully.
http://fivethirtyeight.blogs.nytimes.com/2012/06/20/outlier-polls-are-no-substitute-for-news/?utm_source=twitterfeed&utm_medium=twitter
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