From Huffington Post:

The high rate of teachers cycling in and out of schools is detrimental to the education profession and worse for students, decades of policy and research asserts. But a new report from an influential advocacy group makes the case for treating teacher turnover differently.

The study, called “The Irreplaceables,” took several years for TNTP (formerly The New Teacher Project) to produce, and asserted that a high rate of teachers moving in and out of the profession isn’t necessarily bad.

“The whole basis of federal education policy since the ’60s has been the idea that if kids got greater access to opportunity, they would do better, so the main focus of policy should be increasing that sort of equity, access to teachers,” TNTP president Tim Daly said in an interview.

Rather, TNTP asserted, a high turnover rate among teachers who are “so successful they are nearly impossible to replace” — the “irreplaceables” — is the real problem. “Our analysis suggests that the problem is not the loss of too many teachers, but the loss of the wrong teachers,” Daly wrote in an e-mail introducing the report.

Using teacher performance data and surveys in four school districts and a group of charter schools, TNTP found that improving schools without doing a better job at retaining “irreplaceables” is nearly impossible, and that poor retention policies “degrade” the teaching profession by not paying special attention to keeping top-performing teachers. It recommended teaching principals to better hold onto “irreplaceables” and to “counsel out” low performers, and revamping policies around teacher management, such as tenure and seniority. TNTP also recommended dismissing teachers “who cannot teach as well as the average first-year teacher.”

TNTP works to place teaching fellows in school districts across the country. The group was carved out of Wendy Kopp’s Teach for America and founded by former Washington, D.C., schools chief Michelle Rhee.

The report is bound to affect policy, given TNTP’s track record — and its splashy release Monday with the National Education Association, D.C. schools chief Kaya Henderson, and U.S. Secretary of Education Arne Duncan. “TNTP’s report documents in painful detail that school leaders are doing far too little to nurture, retain, and reward great teachers — and not nearly enough to identify and assist struggling teachers,” Duncan said in a statement. And many cite TNTP’s 2009 Widget Effect report, which revealed the underutilization of teacher evaluations, as a driver of the Obama administration’s Race to the Top Competition.

But the report’s definition of “irreplaceables” is fuzzy, and varies across the school districts that were surveyed. Matthew Di Carlo, writing on the blog of the Albert Shanker Institute, which is affiliated with the American Federation of Teachers, said the “irreplaceables,” as defined by the report, are better described as “probably above average.”

The politics around the report spotlight the making of education advocacy research. In the report’s acknowledgements, TNTP thanked the Bill & Melinda Gates Foundation, the Laura and John Arnold Foundation and the Walton Family Foundation, among others, for support. These organizations pay to push policies known as education reform that make it easier to fire teachers based on students’ low standardized test scores — and reams of research to support that conclusion.

“There’s been a massive investment in research to support the reform theory,” said Craig Jerald, an independent education consultant who has done research for both Gates and teachers’ unions. This research, along with reform advocacy, has forced teachers’ unions to express, for the first time, concern with the low performers among their ranks. While the distinction isn’t that clear cut, in general, the reformers and unions have different ways of approaching these low performers. Unions stress improving them through professional development. Reformers, including the authors of the TNTP report, want to get them out of the classroom faster. “People who support the development side haven’t supported much quantitative research,” Jerald said.

Jerald said he expects the report’s claim that most low-performing teachers don’t improve to be its most controversial. “It’ll force people who disagree with that to go out there and do some research,” he said. “I can’t think of any quantitative research that disputes that.”

TNTP researchers used value-added measurements — a widely used metric that is supposed to tease out teachers’ effects on students’ standardized tests — based on only one year of teacher performance in some cases. The single-year metric is known to be unreliable. “Using multiple years of classroom observations for teachers will reduce sorting bias in value-added estimates,” wrote Cory Koedel, a University of Missouri economist known for his expertise on value-added, in a 2009 report. “This result raises concerns about using single-year measures of teacher value-added to evaluate teacher effectiveness.”

Koedel, however, served on the advisory board of experts that helped guide the TNTP paper. He said his concerns about using such measures have been mostly assuaged by a 2011 Harvard study that found that a teacher’s single-year value-added measures modestly affect students’ earnings later in life. Differences in identifying “irreplaceables” between districts, he said, are “something to be thoughtful about,” but don’t affect the report’s qualitative conclusions. “There’s all kinds of studies in academic literature in terms of teacher turnover, a generic thing,” Koedel said. “The thing is we want good teachers to stay and bad teachers to leave.”

Randi Weingarten, president of the American Federation of Teachers, called the report “puzzling.”

“On the one hand it makes the point of the importance of keeping good teachers and what’s needed to do that,” Weingarten said in a statement. “On the other, it assumes that someone can magically become a good teacher and that school leadership means simply firing bad teachers. What is missing is the work that needs to be done to create continuous development and support systems to help all teachers become great teachers.”