Predicting the Coming GOP Wave

More bad news for the Democrats: A group of political scientists have crunched the numbers and are predicting a 50 seat gain for the GOP in the House.

Political scientists Joseph Bafumi, Robert S. Erikson and Christopher Wlezien predict a 50-seat loss for Democrats in November. They write:

How many House seats will the Republicans gain in 2010? . . . Our methodology replicates that for our ultimately successful forecast of the 2006 midterm. Two weeks before Election Day in 2006, we posted a prediction that the Democrats would gain 32 seats and recapture the House majority. The Democrats gained 30 seats in 2006. Our current forecast for 2010 shows that the Republicans are likely to regain the House majority. . . . the most likely scenario is a Republican majority in the neighborhood of 229 seats versus 206 for the Democrats for a 50-seat loss for the Democrats.

How do they do it? First, they predict the national two-party vote using the generic polls (asking voters which party they plan to vote for in the November congressional elections). Then they apply the national vote swing on a district-by-district level to predict the outcome in each district. They account for uncertainty in their predictions (I assume by using a model similar to what Gary King and I did in 1994), which induces a probabilistic forecast of the number of districts won by each party.

Regular readers will know that this is not news. Way back in September, 2009 -- over eleven months ago -- we used an earlier version of the Bafumi/Erikson/Wlezien model to predict a Republican House takeover in 2010. As I wrote several months ago, it feels good for once to be ahead of the story.