July 24, 2015
A high-stakes birth lottery in the U.S., Stanford researchers say
A new study by Stanford researchers describes how American children born into high-income families can expect far greater earnings and income over their lifetimes than children born into low-income families.
By Clifton B. Parker
This photo from 2013 shows Renee Adams, left, posing with her mother Irene Salyers and son Joseph, 4, at their produce stand in Council, Va. According to a new study by Stanford researchers, children born into low-income families are likely to earn far less during their lifetimes than children born into families with higher incomes. (AP Photo/Debra McCown)
When one wins the "birth lottery" by being born into a higher-income family, the economic payoff is very large, according to Stanford researchers.
"This result is not consistent with the American dream in which children from low-income families are supposed to have ample opportunities for economic mobility," said David Grusky, the director of the Stanford Center on Poverty and Inequality.
In a new study of economic mobility, based on tax data, the gap between this ideal and the reality of the U.S. economy is shown to be very large, Grusky said.
"The American dream is about ensuring that all children, no matter how poor their parents may be, have an opportunity to be mobile by climbing the economic ladder and moving into a higher income group," he said.
Pablo Mitnik, a research associate at the Stanford Center on Poverty and Inequality and lead author of the report, said the research is based on a measure of economic mobility known as the "intergenerational income elasticity," which reveals the economic payoff of being raised in a higher-income family.
In a society with perfect mobility, this elasticity would equal zero and there would be no economic payoff, on average, to being raised in a higher-income family. Although Mitnik noted that it is well-known that the elasticity is much larger than zero, there has been uncertainty in prior research about exactly how large it is.
The elasticity is a concrete measure of the payoff to being raised in a higher-income family. "This measure tells us how much the adult income of children increases with each additional percent of parental income," Mitnik said.
In other words, if children from families making $50,000 per year are compared with those from families making $60,000 per year, this measure describes how much of that 20 percent difference is carried forward into the adult lives of those children, according to Mitnik. If the elasticity were one, then the full 20 percent advantage would be passed on.
The study revealed that the elasticity is very large: The family-income elasticity is .52 for men and .47 for women.
"These two estimates, both of which are toward the high end of the existing range of estimates in the research literature, indicate that approximately half of parental income differences are passed on to children," Mitnik said. Similarly, the elasticity for individual earnings (wages and salary from someone's job) was as high as .56 for men.
It is noteworthy, Grusky said, that the family-income elasticities for men and women are quite similar (.52 for men and .47 for women). This means that they obtain roughly the same total-income benefits from being raised in higher-income families.
But the research also shows that the earnings elasticity for women, .32, is much lower than that for men, .56.
Though women raised in higher-income families benefit less when it comes to their own earnings, Grusky said that this disadvantage is counteracted by an increased chance of marrying a spouse who will bring money into the family.
"The upshot is that, for women and men alike, the benefits to a higher-income upbringing are substantial," he said.
The purpose of the report, Grusky said, was simply to "present the facts to the public," not to weigh in on whether the country should act on them.
But he added that "insofar as there is a commitment to equalizing opportunity, it will likely require ramped-up policies that go well beyond those that are typically entertained."
Grusky said, "The birth lottery is so consequential that there is no escaping the conclusion that the usual policy interventions are just too narrow-gauge and incremental to get the job done."
The problem with prior research, Mitnik said, is that a host of methodological complications made it difficult to measure the elasticity. These problems include small sample sizes, missing data or measurements taken too early in peoples' lives.
Mitnik and Grusky said their research overcomes these problems by advancing new methods and relying on a new high-quality data set based on tax and other administrative records.
This data set, Mitnik said, was developed within the Statistics of Income Division of the Internal Revenue Service (IRS) under the guidance of co-authors Michael Weber and Victoria Bryant of the IRS Statistics of Income Division. During the research, all access to tax data was limited to Weber, Bryant and other IRS employees per IRS rules.