How Out Of Touch Are The Politicians?

Yesterday on this site, Geoffrey Kabaservice wrote:

Every reliable survey reveals a bell curve distribution of American political opinion. A solid majority of Americans, usually some 70 to 80 percent of the electorate, holds basically moderate views, center-left on social issues and center-right on economic issues. And yet, oddly, the overwhelming majority of elected officials represent the most extreme 10 percent on either side of the spectrum.

I don't disagree with the general direction of this claim: politicians differ systematically from voters, typically taking more extreme positions, on average, than most voters.

But I don't know where he got his numbers about "the most extreme 10 percent." Based on the data I've seen, this claim is a bit, well, extreme.

From Michael Herron and Joe Bafumi (and in chapter 8 of Red State, Blue State), here are estimates of the distributions of voters (in 2006), House members, and Senators on a common scale:

House members and Senators' positions are estimated based on their votes in Congress. Voters' positions are estimated based on some survey questions where people were asked their views on a number of issues that had also been voted on in Congress. As you can see, elected representatives are generally more extreme than voters. (See here for versions of the above graph broken down by red, purple, and blue states.)

So, yes, Congress members tend to be more extreme than voters -- or, to put it even more precisely, Congress members tend to be more ideologically consistent than voters do -- but the "extreme 10 percent" thing seems to be overstating it.

See here for further discussion of this point, in the context of the debate over whether America remains a center-right nation.