Poll trolls

There is every reason to expect a landslide in next week’s US elections. I expect Obama to win with more than 300 EVs, and the Dems to pick up maybe 8 Senate seats (VA, NM, AK, NC, CO, NH, OR, maybe MN and GA at a pinch) and 30-40 House seats.

But, Faux News is at it again, touting the race as a “toss up”, narrower than the margin of error. So, one more time, here’s why they’re way out.

First, they’re reporting just one poll. Guess what? The others don’t paint the same picture. [Update: Fox’s poll has already been shown to be a dud, with party identification at 41% Democratic, 39% Republican.]

Here’s the picture you get aggregating the daily tracking polls:

Obama opened up a large gap in mid-September, and has maintained a large lead ever since, with a slight narrowing in recent days. This narrowing was expected, and is considered quite normal. Underpinning Obama’s continuing lead has been a realignment of perceptions of the candidates, reflected in the candidates’ favourability and trust ratings.

Not only has the “horse race” been a picture of remarkable stability, but things have been getting worse for McCain in recent days. The race is about winning electoral votes state-by-state, and not the popular vote. Ask Al Gore.

As of today, aggregating state-level polls shows Obama ahead by at least 8% in states with 272 EVs — enough to win — and by 6%–8% in states with a further 29 EVs and ahead in states with 56 EVs. And Obama is above 50% in the states where he is 6% or more ahead, except Ohio (49.5%). Apart from Missouri and Indiana (which remain toss-ups), the news in the last few days has been good for Obama: his lead has widened slightly in Florida, and remained steady in Ohio, Virginia, Colorado, New Mexico and Nevada.

Here’s RealClearPolitics’ changes in the status of swing states in recent days:

10/30 Pennsylvania Solid Obama »»» Leaning Obama
10/29 Nevada Toss Up »»» Leaning Obama
10/29 Georgia Leaning McCain »»» Toss Up
10/28 New Hampshire Leaning Obama »»» Solid Obama
10/27 New Hampshire Solid Obama »»» Leaning Obama

But the national polls are showing a great deal of variation, you say (correctly). Suppose there’s a lot of hidden support for McCain? Well, you’re right to have doubts about the polls, but if there’s any hidden support, it’s likely Obama’s…

Polls: Caveat Emptor

First, unlike NZ, turnout in the US has historically been a problem, so the data used are “likely voters” rather than registered voters. How do you know who’s “likely” to vote? Traditionally, pollsters put more weight on past voting behaviour as opposed to expressed intentions. Fine, for your average election. But this is not going to be an average election.

Obama’s margin appears to be over 30% with young voters and over 80% of African American voters. Young voters and African Americans have tended to have low turnouts in the past. However, voting in the primaries, early voting so far in the 31 states that allow it, and unprecedented volunteer activity all point to this being an exceptional year for young and African American turnout.

How much difference will this make to the result? Well, Gallup started producing two figures a couple of weeks ago, using the traditional likely voter model and an expanded one that gave greater weight to expressed intentions. The latter has been tracking at around 3–4% above the former, so that’s how much you could add to Obama’s figures in most national polls if you think that next week will see a massive turn-out.

The so-called Bradley effect? As Mark Blumenthal says, “Much of the recent debate centers on whether the effect ever really existed (see the skeptical take by ABC’s Gary Langer) or whether it existed and then disappeared 10 or 15 years ago (see the exhaustive report [PDF] by Harvard political scientist Daniel Hopkins).” There wasn’t any evidence of such an effect in the primaries either, please note.

Then there’s the cellphone-only voters. If anything, this adds another couple of percent to Obama’s total in the polls (here for earlier post).

But what about those polls showing a narrow gap? Like that IBD/TIPP poll that Faux News was salivating over last week? Well, it showed McCain leading by 52 percentage points among 18- to 24-year-olds. Incredible. As in, not credible.

Zogby, another Faux News favourite in recent times? Turns out that Zogby weighting his data by party ID (a common practice stateside) based on 2004 partisan identification. So he’s been weighting so that Republicans are about even with Democrats. Rasmussen, using current partisan identification weights his data 40.0% Democratic, 32.8% Republican, and 27.2% unaffiliated. (Even so, Zogby has Obama 7% ahead today.)

The late deciders you say? (Well, McCain’s claiming they’ll vote his way when they get into the voting booths.) The best analysis suggests that they will split fairly evenly, maybe a little towards McCain. Anyway, even if he got every last one of them, he’d still be behind in the swing states, as Obama is over 50% already.

This is a truly exciting contest, and it may be close, but it ain’t close yet.

Update: Friday evening US-time: McCain claims, “We’re coming back strong.” Reality: RealClearPolitics poll average had Obama’s lead slipping from 8.0% on 25 October to 5.8% on 30 October. Now it’s back up to 6.5%. McCain’s own state is now categorized as a “toss up” and Obama’s campaign has started running ads there. Comeback?! Strong!?

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2 Responses to “Poll trolls”

  1. Democrats On Best Political Blogs » Blog Archive » Poll trolls Says:

    […] Poll trolls So he’s been weighting so that Republicans are about even with Democrats. Rasmussen, using current partisan identification weights his data… […]

  2. adamsmith1922 Says:

    JP

    AM enjoying your series of posts on the US Elections immensely

    Well done

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