Two years ago I released ideology scores for each Utah legislator who served between 2007 and 2011. Today I’m releasing an update that extends the scores through 2013. (Thanks to my research assistant, Justin Chang, for invaluable help.) I’ve written in more detail about the methodology behind the scores in the past.
Please take a moment to understand the origins and limitations of these ideology scores.
- I use the W-NOMINATE algorithm, originally developed to study the U.S. Congress, and widely used among political scientists for that purpose.
- The W-NOMINATE algorithm takes account of every vote cast on the floor of the Utah House or Utah Senate.
- Scores are relative. That means there is no score that means “liberal” or “conservative.” A score of +43 or -21 means nothing by itself. But a legislator with a score of +43 is relatively more conservative than a legislator with a score of +38, who is, in turn, relatively more conservative than a legislator with a score of -4. Higher scores are relatively more conservative than lower scores.
- Scores are placed on an artificial score ranging from -100 (more liberal) to +100 (more conservative), but a score below 0 does not mean “liberal,” just as a score above 0 does not mean “conservative.” Rather, because scores are relative within the Legislature itself, then 0 simply indicates the legislator at the ideological center of his/her chamber. Because the Legislature is over 80% Republican, the 0 point will almost certainly be occupied by a Republican.
- Scores are comparable only within a single chamber, and only within a single year. You cannot compare a House score to a Senate score, or a 2008 score to a 2012 score. Why? Because the scores are relative within each chamber and year. Even if every legislator, Republican or Democratic, moved dramatically to the between year X and year Y, the scores would still be forced by the W-NOMINATE algorithm to fall between -100 and +100 each year.
The complete scores are available on my personal website. You can start here: House (2013) and Senate (2013).
I’ll post some followups in coming days making use of these scores. The main purpose of this post is just to explain how the scores work so that I have something to link to when future posts make use of them.