Nate Silver's response to the Newsweek and Gallup polls.

[FBaggins]

‘Likely Voter’ Gap Favors G.O.P. by 6 Points; Gallup’s Model Sees It Bigger

Democratic poll-watchers were having a pretty good Monday. Rasmussen Reports had shown Republicans with a relatively small 3-point advantage on the generic ballot — the narrowest advantage that Rasmussen has shown for Republicans in about a year. Meanwhile, two polls in a pivotal Senate race, Connecticut, showed the Democrat Richard Blumenthal with a solid lead there. Perhaps there was something to all the talk about a Democratic rebound in the polls, which has been in fashion lately.

But then at about 5:45 p.m., this poll — Gallup’s weekly tracking of the generic ballot — hit the newswires. The poll gave Republicans a 3-point edge among registered voters — well within the range that Gallup has shown in recent weeks. But Gallup also introduced its likely voter model this week, and there, Republicans’ advantage was much larger: 13 points under one scenario — what Gallup calls a “higher turnout” scenario — and 18 points in another, “lower turnout” version of the model. Those are absolutely terrifying numbers for Democrats.

...snip...

I would note, however, that this is exactly why you don’t want to base your model on just one indicator –like Gallup’s likely voter model at the exclusion of all others (or Newsweek’s, for that matter) — when many other relevant types of information are available. Gallup’s model could be right: it is one of the finest polling organizations on Earth, and its likely voter model has a good track record in past midterm cycles. But the results it is showing diverge quite a lot from the consensus of generic ballot polls (moreover, the average of generic ballot diverges somewhat from several other useful indicators, like local polls). Trading markets on the likelihood of a Republican takeover of the House, which are going to do a more robust job of incorporating different types of information than a one- or two-factor model would, were essentially unchanged on the release of both the Newsweek and the Gallup polls, which is probably the most appropriate response.


http://fivethirtyeight.blogs.nytimes.com/2010/10/05/likely-voter-gap-favors-g-o-p-by-6-points-gallups-model-sees-it-bigger/#more-1773

[msongs]

1. Silver is now an employee of the NYTimes nt

[Upton]

2. So's Paul Krugman.....so what?

[FBaggins]

4. Obviously he's now part of the media spin machine that is trying to control us.

How could you miss that?

He sold out for a paycheck of course. </ sarcasm>

[GSLevel9]

6. yeah, wonder how he "cashed out"... probably a wealthy man now. nt

[Grown2Hate]

3. So, their "likely voter model" is assuming a 13 to 18 point swing in favor of

Republicans, but what does that mean? Are they factoring in "the enthusiasm gap" on their own? Where do they get that 13-18 point swing, if the generic ballot has us within 3 points (or tied, or AHEAD in some cases)? Color me confused...

[FBaggins]

5. It's more like a 10 to 15 point swing.

Since their RV results were R+3.

Are they factoring in "the enthusiasm gap" on their own?

Yes and no. There are two different (though related) factors here. Polling firms ask some pretty standard questions (with some variations) that they use to determine whether you are likely to vote. Some of them (prior voting behavior and the amount of attention you've paid to the race) are not "enthusiasm" questions... and most polling firms go that far.

Gallup, OTOH, is reporting multiple results depending on turnout. They take an interesting tack by assigning a voting likelihood percentage based on the answers to those questions as well as some that are more "enthusiasm" related ("are you more or less anxious to vote than last time") then they develop a model that says "if there's 40% turnout then we draw the line here... but at 45% turnout we include these 68 samples...etc.)

There are other ways to do it. They could take those percentages and include the entire sample... but weight each category by that individual likelihood to vote. My guess is that this would have resulted in a 3-5 point smaller gap.

[Grown2Hate]

7. Thank you for the clarification. NT