Descriptors or Treatments

I too have often thought of background variables, such as race, income, and education as descriptors, rather than treatments. However it seems as if most applied econometricians today think of them as treatments. Andrew Gelman posts on this topic:

Income, education, and religion as "background variables" or "treatments"

The discussion here on the climate change attitude mystery reminded me of a funny thing about how we think when we classify people by education, or income, or religion.

The original question was to explain why college-educated Republicans are less likely (compared to non-college-educated Republicans) to believe in human-caused global warming, while, among Democrats, those with college education are more likely to believe in it. To me this was no surprise: college-educated people are more political polarized and are more likely to align their views with their political attitudes.

But many of Tyler Cowen's commenters had a different sort of explanation, along the lines of, Going to college makes Republicans more skeptical of scientific authority but convinces Democrats of these arguments.

Setting aside the specific issue of climate change, one interesting thing here is the way I, in common with most political scientists, think of education (and other variables such as income and religion) as traits, or background variables, or descriptors of people. Thus when we talk about how rich and poor people vote, or more and less educated, or Protestants and Catholics, or whatever, we think of these as different sorts of people. But you can also think of income, or education, or religious attendance, as "treatments" that affect people--for example, if you go to college and share a room with someone of a different ethnic or political group, you might become more tolerant. Or maybe if you are conservative and go to college, you'll be skeptical of what's taught in your physics class (or if you're liberal, maybe you'll be skeptical of what's covered in your econ class).

I don't really have much to add here . . . somehow it seems more reasonable to me to think of these as descriptors than as treatments, but I guess it depends on the person and on what issue is being considered.