Putting a dollar figure on the quality of teaching

Photo: Harvard University News Office

This year’s crop of MacArthur Genius Grant honorees includes a young economist whose work has shown that increasing the quality of teachers can result in tremendous economic benefits.

Raj Chetty, of Harvard, is only 33 but he’s already helped lead two studies that made news because they quantified the value of teachers. As the New York Times writes:

One study released this year, conducted with economists at Harvard and Columbia, tracked one million students in a large urban school district over 20 years and calculated that replacing an average teacher with an excellent one would raise a single classroom’s lifetime earnings by about $1.4 million.

Good teachers who lifted standardized test scores also had students less likely to become teenage parents and more likely to attend a good college, among other positive results.

The study, released in January, studied more students over a longer period of time and used more data than many earlier studies. It was thus the largest look yet at “value-added ratings,” which attempt to measure the impact that individual teachers have on students.

A controversial topic, it’s at the heart of many current debates roiling school districts and teacher unions.

Chetty and his co-authors John Friedman, of Harvard, and Jonah Rockoff, of Columbia, both economists, found that replacing a poor teacher with an average one would raise a single classroom’s lifetime earnings by about $266,000. Keeping a poor teacher in place over 10 years, therefore, is like losing $2.5 million in potential income, the researchers concluded.

Chetty said he began as a skeptic of value-added metrics, believing that factors such as students’ socio-economic backgrounds or motivation were being slighted.

But controlling for numerous factors, including students’ backgrounds, the researchers found that “the value-added scores consistently identified some teachers as better than others,” the Times reported, “even if individual teachers’ value-added scores varied from year to year.”

After identifying excellent, average and poor teachers, the economists then set out to look at their students over the long term, analyzing information on earnings, college matriculation rates, the age they had children, and where they ended up living.

The results were striking. Looking only at test scores, previous studies had shown, the effect of a good teacher mostly fades after three or four years. But the broader view showed that the students still benefit for years to come.

Students with top teachers are less likely to become pregnant as teenagers, more likely to enroll in college, and more likely to earn more money as adults, the study found.

The authors’ conclusion: Use value-added measures in teacher evaluations and remove the worst performers — no matter how disrupting it is.

The MacArthur Fellows Program awards are given every year to about 25 of America’s brightest minds by the John D. and Catherine T. MacArthur Foundation. The grants can’t be applied for. They just drop into the winners’ laps: $100,000 a year for five years.

Chetty was born in New Delhi and raised in the United States from age 9 by his economist father and physician mother. He graduated from Harvard in 2000 and had his doctorate three years later. He was a tenured professor at the University of California-Berkeley at 27, before returning to Harvard three years later as its youngest tenured professor.

“I’m motivated to ask these questions about why some students have good outcomes and some do not by reading the paper or observing the real world,” Chetty told the Times. “At a broad level government policies can impact people’s lives, but we often don’t have the scientific evidence.”

He is already immersed in his next project, the Times said. It explores what factors allow children to move up the economic ladder, relative to their parents.

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Posted on October 3, 2012, in Reading, Teaching and tagged , , , , , , . Bookmark the permalink. Leave a comment.

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