The Mystery Graph….We have put up a short post on TPMCafe explaining how we produced the figure on p. 27 of Off Center (the figure is reproduced by Kevin here) which shows that Republican activists — always farther from independent voters on a liberal-conservative scale than Democratic activists — have moved even farther away in recent years, while Democratic activists have moved back toward independent voters.
A few quick additional clarifications in response to queries we have received:
1. The graph is based on “thermometer” or feelings scores, which are imprecise, though commonly used. (The eminent political scientist Morris Fiorina did a similar analysis showing that party activists were moving farther apart a few years ago (see Figure 6), but without the crucial additional inquiry into whether they were moving away from the middle in equal degree. As we argue in the book, just talking about “polarization” misses the extent to which most of the movement has been on the right.)
2. Using independent voters as a proxy for the “center” was statistically convenient, but probably not ideal, so we have since re-run the analysis using the median liberal-conservative index of all voters as the reference point. The bottom line: Republican activists are slightly closer to the “center” overall but still farther away than Democratic activists, and the trend is basically identical.
3. As we say in our post on TPMCafe, the numbers do jump around from year to year. (For one thing, the number and character of activists differ between presidential election years and mid-term elections.) That is why we used a smoothed trendline. The overall trend, however, is quite clear.
If you managed to keep awake through that, stay tuned for our answer to Kevin’s big question: Are the Republicans cracking up? Are we witnessing the re-assertion of the vital center?