Posted by Jay Livingston
Matt Yglesias posted at this chart of poll results in eight states that elected Republican governors. In seven of the eight, if the election were held today, Democrats would win.
Matt calls this shift “buyer’s remorse” and takes it as a rejection of GOP policies (his post is here). Gabriel Rossman has a different take.
Repeat after me: REGRESSION TO THE MEAN.Politicos like Yglesias might have overlooked this possibility because regression to the mean is mostly a matter of random “error variation,”* or unexplained variation. Intuitively, that doesn’t seem to fit with political opinions. If I get an unusually high score in a bowling game or a math test, I can try to explain it – something about my footwork or concentration. But I also realize that I may have been playing over my head. I have some sense of my true level of ability. I also know that my scores vary, and for reasons I can’t always explain. If you tell me that my lower score in the next game is regression to the mean, I’m not going argue.
I don’t doubt that some of this is substantive backlash to overreach on the part of politically ignorant swing voters who didn’t really understand the GOP platform, but really, you’ve still got to keep in mind REGRESSION TO THE MEAN.
It’s much harder to think this way about my opinion about the governor or anyone else’s opinion for that matter. Whether or not I’d vote for him is not a sample of my opinion. It is my opinion. It’s not random, it’s not an error, and it’s not unexplained. I know why I would or wouldn’t vote for him, and I figure that the same is true for other voters. So you can see why discussions of political shifts tend to leave out regression to the mean.
Even so, is the political shift here regression to the mean? It might help if we had some idea of what the mean is. Suppose that the mean is 50/50 Democratic/Republican. A shift from 8-0 in favor of the GOP to 1-7 in favor of the Democrats is regression way beyond the mean. So, like Lucy, we still have some splainin to do.
* I do not know, though I should, how this variation came to be called “error” or why we persist in using that term.