Thursday, January 25, 2007

Income inequality in NYTimes

Tyler Cowen has a great piece in the NYTimes on income inequality. He argues that most of the visible income inequality in the US is a result of the population getting older and more educated, as there is more variation in income as people become older and more educated
Much of the measured growth in income inequality has resulted from natural demographic trends. In general, there is more income inequality among older populations than among younger populations, if only because older people have had more time to experience rising or falling fortunes.

Furthermore, more-educated groups show greater income inequality than less-educated groups. Uneducated people are more likely to be clustered in a tight range of relatively low incomes. But the educated will include a greater range of highly motivated breadwinners and relaxed bohemians, and a greater range of winning and losing investors. A result is a greater variety of incomes. Since the United States is growing older and also more educated, income inequality will naturally rise.

Thomas Lemieux, professor of economics at the University of British Columbia, estimates that these demographic effects account for about three-quarters of the observed rise in income inequality for men and 69 to 95 percent of the observed rise in income inequality for women (“Increasing Residual Wage Inequality: Composition Effects, Noisy Data, or Rising Demand for Skill?” The American Economic Review, June 2006). In other words, rising income inequality is not just a result of unfairness or bad public policy.
This is a different story from what I was taught at Chicago -- that rising income inequality was driven by technological change (the forklift put well paid, blue collar laborers out of business). There is a great interview of David Card (of "minimum wage does not increase unemployment fame") where he talks about why that story never made sense to him.
Like a lot of other ideas in economics, I think that “skill-biased technical change” can be pulled off the shelf and used to explain inequality in a very superficial way. John DiNardo (of the University of Michigan) and I were troubled by the fact that there are a lot of patterns and trends in the labor market that don't fit in very well with a skill-biased technical change explanation. We were motivated to embark on a Don Quixote mission, a noble cause that wasn't going to go anywhere [laughs].

One thing we pointed out, for example, is that women are lower skilled than men, if you take the fact that they have lower wages as evidence of their skill. The SBTC theory says that people with lower skills should have slower wage growth than people with higher skills. But over the 1980s, women did much better than men. It's also the case that over the 1990s, women's relative wages were fairly stable again. So there was a long period of stability of women's relative wages, then a period of convergence of women relative to men that ended in 1991-92, and then stability again. That's an important set of trends that SBTC doesn't address. SBTC might be consistent with it; it might not be, but the theory needs a lot of auxiliary hypotheses to work.

The same thing is true with respect to the black/white wage gaps. Blacks earn less than whites, and many people believe that the reason they do so is because they're less skilled. Nevertheless, during the 1980s, the black/white wage differential was stable. It didn't widen as people had predicted it might.

Another trend that didn't fit with the SBTC hypothesis concerns the relative wages of people with different bachelor's degrees. There are a couple of different data sets that collect starting salaries for newly minted B.A.s. What these data show is quite remarkable. Everyone knows that the average wage of young college graduates went up over the 1980s. It wasn't the case, however, that the gains were most pronounced in engineering or science. They were actually greater for graduates in the humanities, which doesn't seem consistent with the idea that there is increasing demand for technically proficient, computer-savvy people.
So while it's not clear why income inequality is growing in the US, it's also not clear why we should care. Tyler puts forth three arguments for not caring: 1) consumption inequality is not growing (in part, thanks to government transfer payments, 2) happiness inequality is not growing, and 3) philosophically, we should care about absolute welfare, not the envy-fueled game of relative welfare.
inequality of consumption — the difference between what the poor consume and what the rich consume — does not show a significant upward trend (Dirk Krueger and Fabrizio Perri, “Does Income Inequality Lead to Consumption Inequality?” The Review of Economic Studies, January 2006).

Studies of personal happiness, based on questionnaires and self-reporting, indicate that the inequality of happiness is not growing over time in the United States. Furthermore, the United States has an inequality of happiness roughly comparable to that of Sweden or Denmark, two nations with strongly egalitarian reputations. (See the symposium in Journal of Happiness Studies, December 2005.) American society offers good opportunities for people to be happy, even if not everyone becomes rich.

The broader philosophical question is why we should worry about inequality — of any kind — much at all. Life is not a race against fellow human beings, and we should discourage people from treating it as such. Many of the rich have made the mistake of viewing their lives as a game of relative status. So why should economists promote this same zero-sum worldview?
To me, the most important inequality question centers around mobility: what happens to someone who is born poor, but is brilliant and hardworking -- can they get ahead? On the flip side, what happens to someone who is born rich, but is stupid and lazy -- do they fall behind?


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