It's the Economy, Stupid

by CA Pol Junkie

The Democrats are going to lose a bunch of seats in the House and Senate today. In the Senate, it ought to be 5-8 seats, leaving the Democrats in charge there. You can find a prediction for every occasion for the House. My look at the polling of individual races leads me to believe Republicans will have a net gain of 30-48 seats, although that could be optimistic for Democrats as House races are hard to poll and are subject to voters making their minds at the last minute. The consensus among the pundit class is a Republican gain in the mid=50's. Nate Silver cautions about the high degree of error in House predictions, giving a 95% confidence range of plus or minus about 30 seats. If the Democrats have a good night, they could keep the House. There are a couple factors which could help Democrats outperform the polls. Polling methodology, like some pollsters ignoring cell phones or confusing enthusiasm for likelihood to vote, could be skewing results toward Republicans. Democratic Get Out The Vote efforts have been superior to Republicans' of late, so unless the GOP has improved their organization Democrats can win a few races with shoe leather.

What will be truly aggravating is the pundit class talking about why the Republicans gained today. For all the discussions of policy and Tea Parties and Barack Obama being a socialist, it just doesn't matter. Via Kevin Drum, an elegant analysis by Douglas Hibbs can predict the results of midterm elections using a simple formula.

The in-party is expected to win a baseline constant of 62 seats, plus a number of seats equal to about 62% of the number won at the previous on-year election (the incumbency effect), minus around 1.4 seats for every percentage point of the sitting president'’s vote margin in the previous on-year election (the balance effect), plus almost 10 seats for every percentage point of growth in per capita real disposable personal income over the congressional term.

The formula works shockingly well for midterm elections from 1950-2006 even though the only variable not decided in the previous election is growth in real disposable income. It's not about health care, or deficits, of tea parties, or anything else - just what voters have in their pockets. It also doesn't matter if Democratic policies help the people more than Republican policies would. It's a cynical but utterly logical way to look at the electorate. The model predicts a Republican gain of 45 seats. If Democrats outperform that, they would be having a relatively good night.