Income Mobility Can’t Explain Away Evidence of Increased Inequality

November 29, 2011 at 8:29 am

Some policymakers, like House Budget Committee Chairman Paul Ryan, have tried to dismiss studies like this one from the Congressional Budget Office showing a large rise in income inequality in recent decades by arguing that these studies do not account for income mobility in America.

Here’s their argument:  the data we have showing rising inequality is based on successive “snapshots” of the income ladder over time, but people are not stuck on the same rung over many years; they move up and down the ladder.  Increased income inequality means the rungs of the ladder are further apart, but if there is enough movement up and down that income ladder, where people are in a particular year would tell us very little about where they were a few years earlier or where they will be a few years later.  If mobility has increased enough, the dramatic rise in income inequality over the past thirty years is not an obvious problem.

The problem is, there’s just no evidence that mobility is increasing, and quite solid evidence to the contrary.

A new paper by Federal Reserve economist Katharine Bradbury clearly documents a statistically significant decline in the rate of mobility.  The slowdown isn’t dramatic; Bradbury accurately labels it “slight.”  But it’s there.

This graph, based on Bradbury’s analysis, shows two measures of family income mobility over ten-year spans:  the share of families in the richest fifth who move down the income scale to the middle or lower fifths and the share of families in the poorest fifth who move up to the middle or higher.

The lines basically drift down starting in the late 1970s, meaning there’s less movement between the rungs on the income ladder.  Bradbury found that the downshift over time was statistically significant (see Table 5 of her paper).

The argument that mobility offsets higher inequality may sound plausible, but the facts don’t support it.

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More About Jared Bernstein

Jared Bernstein

Jared Bernstein joined the Center in May 2011 as a Senior Fellow. From 2009 to 2011, Bernstein was the Chief Economist and Economic Adviser to Vice President Joe Biden, executive director of the White House Task Force on the Middle Class, and a member of President Obama’s economic team. Bernstein’s areas of expertise include federal and state economic and fiscal policies, income inequality and mobility, trends in employment and earnings, international comparisons, and the analysis of financial and housing markets. He is the author and coauthor of numerous books for both popular and academic audiences, including “Crunch: Why Do I Feel So Squeezed?” and nine editions of "The State of Working America." Bernstein has published extensively in various venues, including The New York Times, Washington Post, Financial Times, and Research in Economics and Statistics. He is an on-air commentator for the cable stations CNBC and MSNBC and hosts jaredbernsteinblog.com.

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2 Comments Add Yours ↓

Comments are listed in reverse chronological order.

  1. Roger Lamb #
    1

    The data seem to tell against the thesis of equality-of-opportunity, itself a crucial promise of economic liberalism.

  2. 2

    This is nothing unusual for Paul Ryan. If one argument does not stick, create another one. By choosing Income Mobility for his argument, it creates room for “tinkering” with the numbers, you know, torturing them till they tell you what you want to hear. Also, most people don’t understand what Income Mobility is which gives him more room to put a twist on things. But that is what posts like this are for, debunking erroneous statements.



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