Saturday, October 23, 2010

The Republicans Will Take Over the House

Or at least that's what most political scientists believe.  So how do they know so early?  Whereas journalists and pollsters  rely on last-minute polls and campaign events to read tea-leaves to predict the outcome of elections, Political Scientists believe they can predict the outcome of elections well in advance of the election and often without even knowing who the candidates are.  The bad news is that makes following the horse-race a lot less interesting.  The good news is that the track record of these forecasts is pretty good and less time following the horse race means more time that can be spent following the College football season.

There are lots of these forecasts out there, but one popular one, by Emory University Political Scientist Alan Abramowitz says you can predict the overall seat share in Midterm elections by knowing two things: (1) the result of the "generic ballot"*  in early September and (2) the President's approval in early September.  Other forecasts focus more heavily on the state of the economy, but most of the final predictions end up looking fairly similar.

Below I've plotted the predictions of various political science models, along with the forecasts of, a popular web site by uber-nerd Nate Silver that uses political science methods, but is not written by a political scientist.  I also put in a line that is the average of all of these forecasts.  As most of you know, the Democrats control the House and the Republicans need 39 seats to take it over.  All of the predictions but two show the Republicans moving past the margin number of 39 (yes, that's what the big, red line represents).

It's important to remember that all of these forecasts include lots of caveats and many of them even quantify the probability of error (which I completely ignore in this post). In other words, don't come after these folks if their predictions don't come true.  And if you do, please don't tell them that you read it here.

If you want to read more about these predictions, I encourage you to consult the most recent issue of PS: Political Science and Politics, a journal that dedicated a special issue to forecasting the 2010 midterms  They've made the whole thing available to the public, so browse away.

On a final note: I intend this blog to mostly address local and state issues since lots of impressive folks already post on national politics, and with with more authority and status than I do.  With that said, I can't resist weighing in a little on the national scene from time-to-time.  And with that cautionary note: I'll post tomorrow with similar predictions on the Gubernatorial and Senatorial elections. 

*  Here's the text of a traditional "generic ballot question" "We'd like to get your opinion about how you might vote in the House of Representatives election on November 2nd, 2010. If the House of Representatives election were held today, for whom would you most likely vote? [ASKED OF THOSE WHO HAVE ALREADY VOTED: For which candidate for the House of Representatives did you vote?]?"  The Democratic Candidate?  The Republican Candidate? Other

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