Posted by: Jeff | November 2, 2010

2010 Midterms

Today is election day across the country – no matter who you support, get out there and vote!  A democracy depends on turnout to accurately reflect the desires and positions of the electorate.

This has been a much-heralded and discussed midterm season, and the prevailing opinion seems to be that Democrats will fare very poorly.  Republicans and conservative Tea Party candidates have preyed upon public dissatisfaction with the state of the economy and the public spending represented by the economic stimulus package to legitimatize incumbent candidates across the country.  Particularly in the House of Representatives – where every single incumbent currently faces re-election, Democrats are thus very vulnerable.

Two important caveats – one is that things are supposed to be pretty fluid in the House of Representatives.  The Founders set up the structure of the legislative branch to counteract itself.  The whims of the people were deemed chaotic and unpredictable, and thus the House was balanced by the more stable Senate, where Senators face re-election only once in every six years.  Likewise, the House was designed to fluctuate more noticeably in terms of prevailing sentiments and geography, with each Representative tied to a very specific geographic location.  One would thus expect that the House may flip to a larger degree than the Senate.

What perhaps makes these midterms more remarkable then, is the fact that many pundits expect a lot of fluidity in the Senatorial elections as well – there are 37 Senatorial elections, of which 19 are Democratic incumbents (or races for a retiring Democrat’s seat).  Of those 19 Democratic seats, only 7 are safe.  On the other side, of the 18 Republican incumbents, only one faces a true challenge.

Caveat number two is perhaps better news for Democrats.  Up until now, the majority of polling data is collected through land-line telephones.  I am not sure why this is news to anyone, but there has been a social shift over the past two years away from land-lines and toward greater mobile phone usage.  Personally, I haven’t had a land-line since my first year of college.  I suspect that many in my age category have similar stories about land-line usage.  As such, skepticism is finally being levied at phone polling data as unrepresentative sampling of the electorate.

In the past, criticism of land-line based polling and sample skewing has always been dismissed by the observation that land-line voters (typically elderly, middle-class, white people) have much higher turnout rates than predominantly-mobile users.  This much is true.  But now statistical guru Nate Silver has added his own quantitative analysis to show that the cell phone effect might indeed be in play this midterm season:

1. The cellphone effect. This one is pretty simple, really: a lot of American adults (now about one-quarter of them) have ditched landlines and rely exclusively on mobile phones, and a lot of pollsters don’t call mobile phones. Cellphone-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 4 points against Democrats, even after demographic weighting is applied.

There is also some indirect evidence for the cellphone effect. What follows is a list of each firm’s final generic ballot poll, arranged from the best result for Democrats to the worst:

You can see that there is a rather strong relationship between whether a company included cellphones in its sample or not and the sort of result they showed. The polls that were conducted without cellphones showed Republicans ahead by an average of 9.3 points; those with them showed a smaller, 4.8-point advantage. That’s a difference of 4 or 5 points (and one that is statistically significant at the 95 percent confidence threshold), which is about of the same magnitude that Pew identified.

Now, this probably does not mean that Democrats are bound to overperform their polls by four or five points. A fair number of polls do include cellphones, so at best it might be half that. And the effects probably aren’t so uniform from company to company. Still, this is a theory that has a fair amount of evidence behind it.

This will be an interesting thing to watch tonight as electoral results start to pour in – will Democrats out-perform the polling data that suggests a liberal slaughter today?  Perhaps.



  1. 2010 Midterms « The New Millennial…

    Here at World Spinner we are debating the same thing……

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