The learning gap between rich and poor students hasn’t changed in decades

The average performance of the lowest income students in the United States lags about three to four years behind that of the highest income students — an achievement gap that has remained constant for more than four decades, a new study finds.

An analysis of standardized tests given to more than 2.7 million middle and high school students over almost 50 years suggests that federal education programs aimed at closing that gap are falling short, researchers report online March 18 in the National Bureau of Economic Research. Lower achievement in high school leads to lower earning potential throughout adulthood, says coauthor Eric Hanushek, education economist at Stanford University. “The next generation is going to look a lot like this generation. Kids from poor families will become poor themselves.”  

Whether the problem is worsening, however, is up for debate. A widely cited 2011 study, also out of Stanford, showed the achievement gap widening between children born in the mid-1970s and those born in the early 2000s. But Hanushek says his work suggests the gap is holding steady, but isn’t worsening, as previously believed.

He and colleagues looked at results from four different programs conducted nationwide at various intervals from 1971 to 2015 to test teenagers in math, reading and science. A total of 98 exams were used in the programs, testing 13–15 year olds as well as 17 year olds.

To categorize students by family income level, the researchers relied on demographic surveys given alongside the standardized tests that included information on parents’ education levels and other lifestyle indicators. For example, a dishwasher in the 1950s was seen as a wealth indicator. More recent signs of wealth include whether a student has a separate bedroom or a personal computer. 

Test scores for 17-year-old students in the bottom 10th income percentile were far lower than those in the top 10th percentile — suggesting the poorest students’ learning was about three or four years behind that of the richest, the authors report.

Meanwhile, the overall test scores themselves didn’t shift for 17 year olds during the study period. They did improve slightly for 13-15 year olds, but with the lowest-income students still scoring much lower than highest-income students. That suggests that federal programs for younger students have been helpful, including the Head Start preschool program for needy families, or the No Child Left Behind initiative setting academic standards and testing programs for grades 3 to 8, Hanushek says. Programs for older students are sorely needed, he says.

The 2011 study also shows the poorest students about three to six years behind their wealthier peers in terms of learning. But that study, conducted by Stanford education sociologist Sean Reardon, suggests that the achievement gap has been growing wider for decades. The 2011 study looked at 12 exams administered from 1960 to 2007, and found that the gap in test scores between the poorest students and the wealthiest grew by 40 percent from the 1970s to the early 2000s. Reardon suggested parents with means were increasingly investing in their children’s education, exacerbating the divide.

The differing results between the new study and that conducted in 2011 come down to the fact that the researchers analyzed results from different tests and family income assessments, says education sociologist Anna Chmielewski at the University of Toronto, who was not involved in either of the studies.

Hanushek and Reardon agree that the income-related achievement gap is alarming. “That shouldn’t be obscured by academic quibbling,” Reardon says.