The most overrated polling data in politics

I've long argued that the media tends to make too much of polling that consistently shows many more Americans self-identify as conservative than as liberal. News reports often portray that data as evidence that America is a conservative nation, use it to justify assumptions about which policies (and politicians) will be popular, and to assert that Republicans -- but not Democrats -- can enjoy electoral success by appealing to their “base.”

It seems obvious that the public's ideological self-identification cannot carry all that weight. Otherwise, how would you explain (for example) the fact that Democrats have won the popular vote in four of the past five presidential elections? How would you reconcile the preference for the “conservative” label with a general preference for liberal policies?

The significance of the public's preference for a given label is limited by the clarity of that label. A poll asking whether people are Yankees fans or Red Sox fans will yield pretty reliable results: There isn't much danger that different respondents will have significantly differing interpretations of those two choices. That isn't the case with “liberal” and “conservative,” which are relatively abstract labels with imprecise meanings that are rarely articulated for a mass audience, and which simply don't mean much to most people.

The fact that more voters self-identify as “conservative” than “liberal” doesn't tell us nothing. It's reasonable to conclude, for example, that “liberal” may be a more effective insult than “conservative,” and “conservative” a more effective validator than “liberal.” But it doesn't tell us much at all about whether voters really are much more likely to be conservative, or to favor conservative policies and candidates. It doesn't tell us nearly as much as many journalists and pundits think it does.

The Washington Post's Ezra Klein makes a similar point today, based on a paper (pdf) by political scientists Christopher Ellis and James Stimson. Ellis and Stimson note:

[T]he preference for the 'liberal' label over the 'conservative' one has been steadily declining since at least the 1970's, even while preferences for 'liberal' public policy—not to mention 'liberal' political candidates—have vacillated, but have not trended downward, during this time period."

As Klein points out, shortly before the 1936 election, in which Franklin Roosevelt won a landslide re-election and Democrats won almost 80 percent of the seats in the House of Representatives a Gallup poll found most Americans self-identified as “conservative.” Here's Klein:

So on the eve of an overwhelming victory for liberalism -- a victory not just at the polls, but in policy -- the country still called itself conservative. In the decades after that, the country would call itself more conservative, but it would become more liberal. It would elect politicians to oversee the vast expansion of Social Security, and the passage of the civil rights bills, Medicare and Medicaid, welfare, the Medicare Prescription Drug Benefit, the Earned Income Tax Credit, and the Patient Protection and Affordable Care Act. It would march toward equality for both African Americans and women, and, it seems, for gays. It would even come to see conservatives defend both Medicare and Social Security as their own.