He also makes a point that deserves emphasis:
Even if certain differences were entirely "explainable" by race--meaning that these patterns occur in the whole population but not when considering whites, blacks, and others separately--this doesn't mean these differences aren't real. As we know from studying public opinion and voting, economic issues are huge, and the correlation between economics and ethnicity (in the U.S. and in many other places) doesn't mean that economics doesn't matter. When trying to understand the differences between Democrats and Republicans on economic issues, I think it can be helpful to understand the economic positions of their voters--conditional on race and also in aggregate. Both analyses are relevant.---
Andrew Gelman, co-author of Red State, Blue State, Rich State, Poor State has pointed out that the '08 Presidential election shows a political money divide similar to the '04 and '00 elections--the poorer the state, the larger the partisan gap between low income voters and high income voters is. Using voters earning less than $50,000 a year and voters earning more than $100,000 a year, there is a correlation of .49 (p=0) between the political money divide (McCain's $100k+ support minus his $50k- support) and a state's median income. Gelman performs a related analysis using the $50k- and $50k+ categories. He doesn't give an r-value, but a reworking of the same yields a nearly identical correlation of .47 (p=0).
One of Gelman's readers (who is a Princeton professor) points out the economic explanation appears to be a product of state differences in racial demographics:
Larry Bartels comments that if you only look at whites, the rich voter, poor voter pattern is similar in rich and in poor states. So one of our main findings from the Red State, Blue State book from the 2000 and 2004 elections did not persist in 2008.That's a perspicacious observation on Bartels' part. Exit polling for '08 breaks down income by race for whites dichotomously, into under $50k and over $50k categories. The relationship between the political money divide for whites and a state's median income do not approach statistical significance (r-value=.14, p=.33).
After presenting the graph above based on Bartels' comments, Gelman closes by writing "Lots of interesting patterns here." But the only pattern the graph reveals is that blue states tend to have higher median incomes than red states do. The color-coding creates the impression that there is a pattern to be observed in this graph, but there is no meaningful relationship between the x- and y-axes, which is the concern of the post. Presenting a color-neutral graph (click to view more clearly) demonstrates that the state distribution looks kind of like an inverted shotgun discharge, not a relationship of any statistical significance. (Gelman apparently uses per capita median income, whereas I use median household income, but the lack of a relationship exists either way).
Gelman's rich state, poor state divide appears to be proxying a racial split more than it is revealing a split along class lines in poor states. In presenting the class hypothesis, he uses three states as examples: Mississippi (poor), Ohio (middling), and Connecticut (wealthy). But these states might be viewed in another way: Mississippi (much blacker than average), Ohio (average in blackness), and Connecticut (less black than average).
Mississippi provides an excellent example of why Gelman's analysis of the political money divide is substantially incomplete in not taking race into consideration. It is the poorest state and also the state with the largest political money divide. Among those making over $50,000, 74% voted for McCain. Among those earning less than $50,000, only 25% did. That's a political money divide of 49. But that gap is almost entirely accounted for by the presence of blacks. Among whites, 84% of $50k- voters backed McCain, while 91% of $50k+ whites did--a PMD of only 7.
On average (mean, weighted), McCain does 6.7 points better among whites making more than $50k than he does among whites making less than $50k. Among all voters, the gap is twice as wide. McCain does 13.4 points better among $50k+ voters than he does among $50k- voters. Half of the PMD used as the basis for explaining the differences in electoral behavior between the rich and the poor is a product of race--it disappears when non-whites are taken out of the equation.
As mentioned previously, the relationship between the white PMD and median income is almost nonexistent. If only the top 25 blackest states and DC are considered, it attenuates to nothing (r-value=.08, p=.72). A tenuous relationship between median income and white PMD does emerge when race isn't a salient factor. In the 25 whitest states, there is a correlation of .29 (p=.16) between white PMD and median income.
Whites simply don't split much along economic lines. This is especially true as the presence of non-whites (specifically blacks, as they are the electorally largest and most 'contentious' minority) increases. Race appears to be more important than class is in determining how people are likely to vote.
I'm skeptical about Gelman's claim that in '00 and '04, whites followed the larger PMD trend that he says did not persist in '08. As he points out elsewhere, state voting patterns changed little between the '04 and '08 elections. Some realignment of the white vote did occur, though. For Gelman's claim to hold, this would have to have consisted of poor whites in the McCain belt turning sharply more Republican than they already had been, and wealthy whites on the West Coast and Northeast becoming more Democratic than they had previously been.
Unfortunately, verification isn't currently feasible. Public exit polls for the '04 Presidential election do not have data broken down by income and by race. For comparative purposes, I've left a request with Gelman to make his data available on an easily accessible medium like Swivel.
Relatedly, I'm also skeptical about one of the book's major selling points:
Myth: Class divisions in voting are less in America than in European countries, which are sharply divided between left and right.Tautologically, I do not doubt it. But I suspect a comparison of white Americans and white Europeans would actually validate the myth. In refusing to consider the enormous importance of race in comparative geographic analyses, we inevitably obfuscate our view of what is going on.
Fact: Rich and poor differ more strongly in their voting pattern in the United States than in most European countries.
Data are here and here.