Conrad Hackett, a postdoctoral research fellow in the Population Research Center at the University of Texas at Austin, has a helpful if wonkish (and expensive) article in the last Journal for the Scientific Study of Religion on measuring evangelicals.
Michael Lindsay, he of Faith in the Halls of Power, cowrote the article and has an executive summary on his website.
But today on The Immanent Frame blog, Hackett summarizes the article with an eye to tonight’s exit poll data:
The question used to identify evangelicals in today’s exit polls is “Would you describe yourself as a born-again or evangelical Christian?” Unfortunately, this is not a great survey question.
One problem with this measure is that it produces estimates of the evangelical population considerably larger and different from estimates based on measures more commonly used by scholars. The measure originates with the Gallup Organization, which has been using it since 1986 to track the size of America’s evangelical population. It was introduced into presidential election exit polls in 2004.
Despite Gallup’s reputation, the measure has several flaws. It is a double-barreled question that implies that “born-again” and “evangelical” are interchangeable labels, which may not be true for all respondents. It does not offer respondents alternate ways of expressing religious identity, which no doubt inflates estimates of the evangelical population. In this respect, a better question would be “Would you describe yourself as an evangelical Christian, another type of Christian, or a non-Christian?”
More helpful analysis follows, including a nod to the problem of asking only white Protestants whether they’re evangelicals or born-again Christians.