(This is cross-posted from ProgressiveFix.com, the new online face of the Progressive Policy Institute, where I will be posting regularly.  Give 'em a look.)

OK, to review the debate so far: I wrote a post suggesting progressives might want to think twice before jettisoning the filibuster. Ed thought twice and said, yup, still want to get rid of it.  Ezra did the sameI wrote another post saying, oh well whatever nevermind and tried to shift the subject to polarization being the real problem. I said I’d follow up about whether increasing polarization has been a one-sided affair. Crickets chirped. All hell broke loose on the health care reform front. And here we are.

So….one-sided polarization….Ever since Jacob Hacker and Paul Pierson’s 
Off Center, all good progressives know that the growing political polarization has been one-sided, with Republicans pulling public policy “off center” through various nefarious means. Right?

Well….yes and no. Hacker and Pierson argued that, as of 2005, Republican activists and legislators had grown more conservative, but Democratic activists and legislators had not grown more liberal (and had even moved to the right themselves in some regards). Along with this shift, Republicans had developed effective strategies to move public policy further rightward than the typical voter preferred.

Since the rightward shift of Republicans occurred during a period in which Hacker and Pierson showed the distribution of self-identified ideology had not changed, the implication was that the electorate was being deprived of the more progressive policies that it desired. But a closer look at their data and analyses shows that while the increase in polarization among legislators has occurred disproportionately among Republicans, the evidence hints that this is because it proceeded from a Nixon-era Democratic Congress that was well to the left of the electorate.

Rather than refuting the idea that policy reflects the preferences of voters in the middle (the “median voter theorem”), as Hacker and Pierson claimed, the evidence actually bolsters this view. Correcting their claims is important if progressives are to govern effectively. Republicans did not simply pull public policy to the right of where Americans preferred, and now that Democrats are back in control of Congress, progressives should not assume that the median voter is leftier than she really is.

Why Off Center Is Off


To argue their case, Hacker and Pierson turned to scores created by Keith Poole and Howard Rosenthal that put members of Congress past and present on a common scale measuring ideological position. Hacker and Pierson report that the polarization of Congress between the early 1970s and the early 2000s was almost entirely due to growing extremism among Republicans. Democratic legislators had not moved nearly as far from the center. Because of the increasing conservatism of Republicans, Congress was, in the early 2000s, far to the right of the median voter, who had not grown more conservative over time. But Hacker and Pierson’s account is flawed.

Consider the Senate.* Poole and Rosenthal’s scores, using every vote by every member of every Congress through the 108th Congress (which ran from 2003 to 2004), indicate that the “center” as of 2003-04 was typified by northeastern Republicans such as Lincoln Chafee, then-Independent Jim Jeffords, and William Cohen; Arlen Specter (now, of course, a Democrat); and by red-state Democrats such as Ben Nelson and John Breaux. In 1971-72, the median senator had a score of -0.056, equivalent to Ben Nelson’s score in 2003-04. By 2003-04, the median senator had a score of 0.061, equivalent to Arlen Specter in 2003-04.

This small change in the median of the Senate as a whole only hints at the fact that, as Hacker and Pierson claim, Republican senators did move farther ideologically than Democratic senators. The evidence that Hacker and Pierson presented describes how the median in one year compared with then-recent senators’ scores. In the early 1970s, according to Hacker and Pierson, the median Republican senator lay “significantly to the left of current GOP maverick John McCain of Arizona—around where conservative 
Democrat Zell Miller of Georgia stood” [where the references to McCain and Miller are to their 2003-04 scores, italics in the original]. The median Republican senator’s score then “doubled” by the early 2000s so that it sat “just shy of the ultraconservative position of Senator Rick Santorum.”

These descriptions do not quite reflect what the Poole-Rosenthal scores show. The median Republican senator’s score in 1971-72 was 
equidistant between McCain in 2003-04 and Miller in 2003-04, not closer to Miller, and it was just as close to McCain as the median Republican senator’s score in 2003-04 was to Santorum.

This claim also raises a technical issue. The Poole-Rosenthal scores are not ratio scales with a meaningful zero point. The distance between 0.2 and 0.4 is supposed to be the same as that between 1.2 and 1.4, but 1.2 is not “six times as conservative” as 0.2, because a score of 0 does not indicate the complete absence of conservatism. The zero point is completely arbitrary. The doubling from 0.2 to 0.4 would become an increase of just 50 percent if we added 0.2 to all of the scores (from 0.4 to 0.6). We cannot know whether Republican senators grew twice as conservative between the early 1970s and the early 2000s. Indeed, the phrase “twice as conservative” has no obvious meaning.

More to the point, Hacker and Pierson’s interpretation of these results is an even bigger problem. Rather than the Republican Party drifting ever rightward (the whole time increasingly “off center”), if the Democratic Party was “off center” in the early 1970s, then the movement among Republicans could be interpreted as a restoration of an equilibrium reflecting voter preferences. This is exactly what appears to have happened.

First of all, the medians for the 2003-04 Senate were 0.379 and -0.381 for Republicans and Democrats – essentially identical. That means that after this great rightward shift by Republicans, the parties were equally “extreme” by historical standards. Furthermore, the median Democratic senator in 1971-72 wasn’t much less extreme than the median senator from either party in 2003-04.

Second, at least in terms of self-identification, the ideological distribution of Americans was unchanged over this period, with roughly twice as many people calling themselves conservative as calling themselves liberal.**

Taking these facts together – a rightward shift by Republican legislators, an end state where Democrats and Republicans are equally “extreme”, and an ideological distribution among voters that was static over the period (and right-leaning) – the conclusion that best fits is that the Democratic Congress of 1971-72 was off center rather than the Republican Congress of 2003-04. The median Republican became more extreme over time, but that was because Congress became 
more representative of the electorate, not less. The story on the House side is much the same, except that the median Republican was a bit more “extreme” than the median Democrat by 2003-04 (although no more extreme than the median Democrat was in 1971-72).

Comparing the Activists


Hacker and Pierson also argue that Republican activists grew more extreme while Democratic activists became less so (becoming even less extreme than Democrats in general), but these claims are also problematic. Hacker and Pierson began by defining an activist as someone who self-identifies as a Democrat or a Republican and who participated in three out of five election-related activities asked about in the American National Election Studies. They measured ideology using a combination of two “thermometer” items – one of which asks respondents how warm or cold they feel toward liberals and one inquiring about conservatives. These scales range from 0 (cold) to 97 (hot). (The scale ends at 97 rather than 100 because in some years, the NES used codes 98 and 99 as missing value codes.) The liberal score is subtracted from 97 (so that high numbers then signify cold feelings) and then added to the conservative score. This number is divided by two, 0.5 is added to it, and the decimal is dropped. The resulting measure ranges from 0 (extremely warm toward liberals and extremely cold toward conservatives) to 97 (extremely cold toward liberals and extremely warm toward conservatives).

To determine how far activists drift from the center, they compared the activist scores on this index to the scores for independent voters. The distance from independents is expressed in percentage terms (e.g., 10 percent more conservative or liberal). Hacker and Pierson plotted the average distance from independents for Republican and Democratic activists and then “smoothed” the trends by imposing curves to describe them. The result is a graph that I replicated, more or less:
Picture
The graph shows that Republican activists were more extreme than Democratic activists to begin with, that they became more conservative over time, and that after becoming more liberal, Democratic activists tacked back toward the center. The first important thing to note about this graph is how much the nice, smooth lines depend on fitting the data points to a quadratic equation. The original data – without the smoothing – looks much messier:
Picture
The upward trend among Republican activists is still readily apparent, but the trend for Democratic activists no longer points toward moderation. The bouncing around is partly due to different turnout patterns in off-year elections, but also a result of statistical noise, as the sample sizes for each group are less than 70 – and as low as 18 – in each year. Furthermore, Republican and Democratic activists are statistically the same distance from the center for much of the period between 1968 and 1992. To illustrate further how deceptive the smoothed trend lines can be, look what happens to them when 2004 data – which was not available when Hacker and Pierson created the graph – is added:
Picture
The Republican line hardly changes, but now Democratic activists appear to grow steadily more liberal. It still appears as though Republican activists drifted from the center more than Democratic activists did, and Republican activists look more extreme in all years.

OK, take a breather. Tomorrow I’ll wrap up with some revealing evidence about how Hacker and Pierson’s definition of “the center” affects these analyses of political activists.

To read the second part of this post, click here.

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* Following their recent book, Polarized America (McCarty, Poole, and Rosenthal, 2006), I use scores on Poole and Rosenthal’s first DW-NOMINATE dimension (for details, see  
http://polarizedamerica.com/ and http://www.voteview.com). Hacker and Pierson report using “d nominate” scores, but these are only constructed through the 99th Congress, so I am inclined to believe that they too used the first DW-NOMINATE dimension scores.

** Hacker and Pierson (2004), page 38. Hacker and Pierson cite ANES data. According to Gallup data showing self-identified ideology, the breakdown among Americans as a whole in 2004 was roughly 20 percent liberal, 40 percent moderate, and 40 percent conservative (Wave 2 of the June Poll, Question D10). In 1972, it was 25 percent, 34 percent, and 37 percent (Poll 851, Question 14).
 


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