Five reasons why Democrats could still turn poll odds and hold House

Though polling data suggests that the Republicans may win the House of Representatives on Tuesday, the Democrats might still be in a position to turn the odds to their favour and hold the House.

Evidence suggests that the Republicans will win the House in a robust sort of way, given the generic ballot poll, or the fact of how badly Democrats are doing among whites, or among independents!

But all of these indicators are, in fact, highly correlated with one another. They’re all rooted in the polling, and they’re all dependent on the polling basically being accurate.

There’s not much diversity at all: it’s just different manifestations of the same thing.

According to the New York Times, there are five reasons why a turnaround is possible.

1. The cell phone effect: A lot of American adults (now about one-quarter of them) have ditched their landlines and rely exclusively on their mobile phones, and a lot of pollsters don’t call mobile phones. Cell-phone-only voters tend to be younger, more urban, and less white — all Democratic demographics — and a study by Pew Research suggests that the failure to include them might bias the polls by about four points against Democrats, even after demographic weighting is applied. There is also some indirect evidence for the cell phone effect. What follows is a list of each firm’s final generic ballot poll, arranged from the best result for Democrats to the worst:

2. The ‘robo-poll’ effect: Unlike in past years, there are significant differences between the results shown by automated surveys and those which use live human interviewers — the ‘robo-polls’ being three or four points more favourable to Republicans over all, although the effects vary a lot from firm to firm. Automated surveys, while they have performed fairly well in the past (although in the past, importantly, they did not show these systematic differences from regular surveys), have a number of potential problems that essentially boil down to extremely low response rates, which could potentially bias the samples. For instance, it may be that only adults who are extremely engaged by politics (who are more likely to be Republican, especially this year) bother to respond to them.

3. Some likely voter models, particularly Gallup’s, may “crowd out” Democratic voters. Gallup’s traditional likely voter model has consistently shown terrible results for Democrats this year, having them down by around 15 points on the generic ballot, which could translate into a loss of 70 to 80 House seats, or maybe even more. The Gallup poll and the Gallup poll alone is probably responsible for much of the sense of impending doom that Democrats feel and the (premature for at least 24 more hours) sense of triumphalism that Republicans are experiencing.

There is quite a bit of room to critique the poll, however. The basic potential issue is that Gallup uses fixed turnout targets. For instance, they estimate that 40% of the electorate will vote, and then let their respondents fight it out to see who the 40% most likely to vote are.

And Gallup’s model can produce some strange effects.

The counterargument would be that midterm election turnout has indeed been extremely stable at about 40% of the population, so Gallup is on solid footing in assuming that it will be somewhere in that range again.

But there is some evidence that turnout might be unusually high in this election: there is no doubt that Republican engagement is likely to be extraordinary, but Democratic involvement, also, in fact appears to be about average or slightly above.

Gallup gets a lot of deference, because it is one of the best polling organisations in the world, and because its likely voter model has done very, very well in predicting the outcome of past midterm elections.

4. Democrats probably have better turnout operations. This is always what a party says when it’s about to lose an election: our amazing turnout operation will save us! Still, Democrats probably do have an edge in this department with the voter lists and infrastructure they built up during Barack Obama’s campaign, and which have been perpetuated to some extent by Organizing For America. John McCain, by contrast, eschewed his ground game, devoting almost all of his money to advertising.

5. The consensus view of Democratic doom is not on such sound footing as it seems. When a party is likely to sustain fairly significant losses in a midterm election — and Democrats are going to sustain fairly significant losses tomorrow — there are a lot of things you might expect to see.

Each of the indicators that I mentioned above is a direct manifestation of polling data. The message in the polls this year is unambiguous: bad things are going to happen to Democrats. The polls are probably going to be right.

Our Congressional forecasting models are based on an intensive study of six political cycles: 1998, 2000, 2002, 2004, 2006, 2008. In five of those six years, the polls were quite good — they missed a few races, but were very strong overall.