The headline for this post is from a researcher quoted in today’s front page article in The New York Times headlined Big Study Links Good Teachers to Lasting Gain.

Here are some quotes from this ringing endorsement of using value-added measures to evaluate teachers:

Replacing a poor teacher with an average one would raise a single classroom’s lifetime earnings by about $266,000, the economists estimate. Multiply that by a career’s worth of classrooms.

“If you leave a low value-added teacher in your school for 10 years, rather than replacing him with an average teacher, you are hypothetically talking about $2.5 million in lost income,” said Professor Friedman, one of the coauthors…

“The message is to fire people sooner rather than later,” Professor Friedman said.

Professor Chetty acknowledged, “Of course there are going to be mistakes — teachers who get fired who do not deserve to get fired.”

This study, the quotes, and the article reinforce the regular message sent by “school reformers” to teachers — we want to figure out how to use teacher evaluations to get rid of you, not help you develop into better teachers. It’s a message that was seconded by today’s Gates Foundation report.

I’m sure that other more capable education bloggers like School Finance 101 or The Shanker Blog will develop a careful analysis of this study. In the meantime, however, I’ll maintain a great deal of skepticism. According to the article, this study focuses on two key questionable beliefs, which you can read more about at The Best Posts Debunking The Myth Of “Five (Or Three) Great Teachers In A Row” and The Best Resources For Learning About The “Value-Added” Approach Towards Teacher Evaluation.

In the meantime, check out the 300 reader comments that have already been left at the article. Diane Ravitch sent out a tweet saying:

“Readers’ comments after article make more sense than the study.”

Also, check-out David B. Cohen’s post on the article.