Matheson’s Congressional votes often go against partisan expectations.
Jim Matheson presents himself to voters as a moderate willing to work with both parties. Critics from the right contend that he’s really a liberal at heart who will promptly ally with Pelosi and Obama when given the chance. It’s time for some hard data.
How we measure US Representatives’ ideology
Political scientists have worked for years to develop reliable ways of estimating the ideology of members of Congress. The best technique produces so-called DW-NOMINATE scores, available for download at VoteView.com. (Regular readers will recall that I used a similar method to estimate ideology scores of Utah’s state legislators.) The DW-NOMINATE algorithm uses all votes cast by members of Congress to line them up from most liberal to most conservative, with scores ranging from -1 (most liberal) to +1 (most conservative).
I stress that -1 does NOT mean “perfect Democrat” and +1 does NOT mean “perfect Republican,” as it’s entirely possible for a person to be far left of the Democrats or far right of the Republicans. These are relative scores, not absolute scores.
Below, you can see how the scores look for the current (112th) US House. The line goes up where there is a greater concentration of scores. You’ll see that there is a big concentration around -0.5 and also around +0.5. This reflects the polarization of the two major parties, with few Representatives in the center.
If I drew a separate line for each party, rather than using one line for all representatives, it would look like this:
The two lines don’t overlap at all. That’s because the most liberal Republican is somewhat more conservative than the most conservative Democrat. (It was common for the lines to overlap a couple decades ago, but that’s another story.)
How Matheson, Bishop, and Chaffetz compare to their parties
Now, let’s go one step further and mark Jim Matheson’s location. Just for comparison, we’ll also add in Rob Bishop and Jason Chaffetz.
It is readily apparent that Matheson is among the most conservative Democrats in the US House. Of 194 Democrats presently serving, only 4 have a score more conservative than Matheson’s. Whether that makes him a “conservative” in absolute terms rather than relative terms is, of course, in the eye of the beholder.
Incidentally, Nancy Pelosi’s score of -0.533 places her well left of center even within the Democratic Party. Fewer than one-quarter of House Democrats are more liberal than Pelosi. There is noticeable ideological daylight between Pelosi and Matheson.
For discussion of Bishop and Chaffetz, read the footnote at the end of this sentence.1
How ideological (or predictable) is Matheson?
The DW-NOMINATE scores also give us an estimate of each Representative’s overall predictability. For most Representatives, you can do a pretty good job of predicting their vote on any particular bill simply by knowing the Representative’s DW-NOMINATE score (and also by knowing how the other 434 members of the House voted on the bill in question).
Usually, predictability is pretty high. As you can see from the chart below, you can predict Rob Bishop’s vote 92% of the time and Jason Chaffetz’s vote 93% of the time. These are typical scores. In fact, Chaffetz sits exactly on the median.
Jim Matheson, meanwhile, is hard to pin down. You can predict his vote only 78% of the time. That might sound high in absolute terms, but in the highly polarized environment of the US House, that’s a remarkably low score. Only 5 of the 435 Representatives have a lower predictability score. From a statistical standpoint, this low predictability score suggests that Matheson’s Congressional votes often go against partisan expectations.
Of course, this analysis does not attempt to address whether Matheson’s voting record is consistent with what voters in Utah’s fourth district desire. Only voters themselves can answer that question.