More on the swing in the House vote

In yesterday’s blog entry I looked that the swing in congressional voting nationally (House Democrats gained 5.7%, on average, compared to 2004) and by state (compared to 2004, House Democrats gained in nearly every state). My graphs elicited several interesting comments including this from Steve Sailer:

Perhaps the reason that the GOP House losses of seats were considered not so bad compared to 2006 was because in 2008 the Democrats ran up huge turnouts in black-represented Congressional districts, which were already all Democratic?

Let’s look at some district-by-district swings, starting in 2002:


Here, I’m excluding uncontested elections and those in which the challenger got less than 10% of the vote; dots indicate incumbents running for reelection, circles are open seats, and red points are those with black representatives as of 2008. (I just pulled the names off the Congressional Black Caucus website and didn’t try to go back to earlier years on this.)

What happened? Overall, the Democrats gained a bit in 2004, a lot in 2006, and some in 2008. But we knew that (see the time series plot in the blog entry linked above). We also see a bit of scatter. Beyond this, yes, there are some patterns. In 2006, the Democrats particularly gained in Republican areas–see how those dots in the lower left of the second graph are way above the 45-degree line? In 2008, the swing is more uniform. (In addition, the black Democrats did pretty well in 2008 compared to 2006, but it doesn’t seem like a big part of the story.)

Returning to the “How well did the Democrats actually do in 2008” question, I think that one problem is that people are comparing Obama’s vote to Kerry’s vote but then comparing the congressional Democrats in 2008 to the congressional Democrats in 2006. I think it’s more appropriate to compare 2008 to 2004 in both cases. As Paul Krugman put it, “Maybe the reason people don’t see this is that the Democratic House gains were spread over two elections.”

P.S. This is about it for now, I think. Time to return to regular statistics posting.