In early December, in Osawatomie, Kan., President Obama delivered the sort of fiery populist speech his base had been demanding since the start of his administration. The speech as a whole strongly overstated the extent of economic insecurity in today’s America, but one particular claim jumped out at me — that upward mobility has declined rather sharply:
We tell people — we tell our kids — that in this country, even if you’re born with nothing, work hard and you can get into the middle class. . . . And yet, over the last few decades, the rungs on the ladder of opportunity have grown farther and farther apart, and the middle class has shrunk. You know, a few years after World War II, a child who was born into poverty had a slightly better than 50-50 chance of becoming middle class as an adult. By 1980, that chance had fallen to around 40 percent. And if the trend of rising inequality over the last few decades continues, it’s estimated that a child born today will only have a one-in-three chance of making it to the middle class — 33 percent.
This claim of falling upward mobility — of diminished opportunity — rang false to me. The figures were new and of unknown origin, and they contradicted most of the research that has been conducted to date. Upward mobility is too limited in the U.S. today, and it is lower than it is in other countries (a fact cited by Rick Santorum
in a recent Republican presidential debate). But upward mobility does not have to be falling for it to be too limited, and there is only the thinnest evidence that it has fallen over time. I suspected that the administration had sought out new mobility figures that would solidify the populist story of diminished opportunity that formed the basis of the Kansas speech (and perhaps of a 2012 campaign narrative).
Further research revealed that the evidence behind the president’s mobility claim is irreparably flawed. His figures are based on a very sophisticated — but unreliable — back-of-the-envelope analysis that was intended to get around data limitations. And this is far from being simply an academic question. In this case bad evidence discourages people struggling to escape poverty. It unnecessarily increases Americans’ anxiety levels and adds to the general sense of gloom that has sapped consumer confidence, thereby increasing the agonizing slowness of the recovery.
First, consider what we know from previous studies of trends in intergenerational income mobility. The bulk of the existing research shows either that mobility has increased over the long run or that it has changed little in either direction. That includes both studies that I know of examining changes in upward mobility from the bottom. It also includes six studies using measures of mobility not confined to movement up from the bottom; these find either no change or rising mobility. In contrast, only two papers find a fall in mobility, each using non-directional measures. Notably, one of them shows an uptick in the mobility of the most recent two birth cohorts it examined, leaving in doubt the question of whether the longer-term decline it found would have persisted had the authors had more recent data. The other study finds somewhat mixed evidence, depending on the data source and whether children of single parents are included.
The research to date has important limitations. Many of the studies cover a small number of cohorts, and all of the ones finding no increase in mobility use the same data set. However, the conclusion that mobility has been flat or rising over the long run is mirrored in studies of trends in mobility over adults’ lives (within a generation) and of trends in occupational mobility. The educational-mobility evidence, to my knowledge, comes from a single study that found mixed results.