Partisan Districts, Partisan Votes

Fight disinformation: Sign up for the free Mother Jones Daily newsletter and follow the news that matters.

John Sides asks today for the single factor that best predicts which Democratic House incumbents lost their seats on Tuesday. It’s not ideology, he says, or how you voted on TARP, or any of those things:

The best predictor by far is none of those. It is simply how Democratic their district is. In our dataset, Eric McGhee and I measure that with the percentage of the vote that Obama received in 2008….In all 402 contested House elections, the 2008 presidential vote in that district would explain 83% of the variation in the Democratic House candidate’s vote share. Nothing else in our dataset comes close.

I’m a big fan of simple structural explanations like this, but I’ve got a big problem here. Sides’s chart is above, and it does indeed seem to show a very clean relationship. But a big reason for that is the large number of districts that are wildly partisan: above 60% is entirely Democratic and below 40% is (almost) entirely Republican.

This is no surprise, and also not very interesting. Of course massively partisan districts are highly likely to return partisan results. For one thing, most of them are hardly even contested.

But what happens if you stay in the general vicinity of the middle? That’s the thick black box I added to to chart, and it shows only districts where Obama won 40-60% of the vote in 2008. I’ve enlarged it on the right. Just by eyeballing it, it looks like there’s still a relationship, but it’s a much weaker one. Note, for example, that the Republican pickups (bright red) are spread fairly evenly across the entire range. The overall regression line might be just as steep (I can’t say just by looking), but it’s definitely a lot muddier. It certainly explains way less than 83% of the variation in the 2010 vote.

A model that gets most of its power from its extremes doesn’t strike me as very explanatory. Everyone knows there’s no action there. What we want is a model that explains what happens in districts that are truly contested. Looking solely at the 2008 presidential votes doesn’t seem to get us very far there.

AN IMPORTANT UPDATE

We’re falling behind our online fundraising goals and we can’t sustain coming up short on donations month after month. Perhaps you’ve heard? It is impossibly hard in the news business right now, with layoffs intensifying and fancy new startups and funding going kaput.

The crisis facing journalism and democracy isn’t going away anytime soon. And neither is Mother Jones, our readers, or our unique way of doing in-depth reporting that exists to bring about change.

Which is exactly why, despite the challenges we face, we just took a big gulp and joined forces with the Center for Investigative Reporting, a team of ace journalists who create the amazing podcast and public radio show Reveal.

If you can part with even just a few bucks, please help us pick up the pace of donations. We simply can’t afford to keep falling behind on our fundraising targets month after month.

Editor-in-Chief Clara Jeffery said it well to our team recently, and that team 100 percent includes readers like you who make it all possible: “This is a year to prove that we can pull off this merger, grow our audiences and impact, attract more funding and keep growing. More broadly, it’s a year when the very future of both journalism and democracy is on the line. We have to go for every important story, every reader/listener/viewer, and leave it all on the field. I’m very proud of all the hard work that’s gotten us to this moment, and confident that we can meet it.”

Let’s do this. If you can right now, please support Mother Jones and investigative journalism with an urgently needed donation today.

payment methods

AN IMPORTANT UPDATE

We’re falling behind our online fundraising goals and we can’t sustain coming up short on donations month after month. Perhaps you’ve heard? It is impossibly hard in the news business right now, with layoffs intensifying and fancy new startups and funding going kaput.

The crisis facing journalism and democracy isn’t going away anytime soon. And neither is Mother Jones, our readers, or our unique way of doing in-depth reporting that exists to bring about change.

Which is exactly why, despite the challenges we face, we just took a big gulp and joined forces with the Center for Investigative Reporting, a team of ace journalists who create the amazing podcast and public radio show Reveal.

If you can part with even just a few bucks, please help us pick up the pace of donations. We simply can’t afford to keep falling behind on our fundraising targets month after month.

Editor-in-Chief Clara Jeffery said it well to our team recently, and that team 100 percent includes readers like you who make it all possible: “This is a year to prove that we can pull off this merger, grow our audiences and impact, attract more funding and keep growing. More broadly, it’s a year when the very future of both journalism and democracy is on the line. We have to go for every important story, every reader/listener/viewer, and leave it all on the field. I’m very proud of all the hard work that’s gotten us to this moment, and confident that we can meet it.”

Let’s do this. If you can right now, please support Mother Jones and investigative journalism with an urgently needed donation today.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate