Sunday, April 15, 2012

The Myth of Growing Income Equality

You hear more and more chanting that income distributions are becoming more unequal. Is that really so? Those who like to think so focus on the distribution of household income, and, indeed, at the household level this is true. The chart below shows a statistical measure of distribution called the Gini Coefficient (a value of zero would occur when every member of the set was exactly equal. A value of 1 would mean one person in the set has all the income). So why is this number increasing? If it were, as the hysterics suggest, a function of increasing income for just a few, the Gini Coefficient would be rising when calculated at the individual level. But it's not. It's flat to down a bit.

The reason the household number is rising while the individual number is flat/down is entirely a function of how people organize themselves into households. This should not be terrible surprising. Like tend to attract like. What's been happening is that those who have higher earning potential are increasingly likely to form families with other people who have higher earning potential. For example, those who went to college are increasingly likely to form households with others who went to college. In fact, Charles Murray recently wrote an entire book about this called Coming Apart.

So if you're really upset for some reason about increased household income equality, you're going to have to focus your attention on the real underlying drivers. Maybe you should suggest to your daughter at college that she look for a husband among the dining hall staff rather than among her fellow students.



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