New York Releases Performance Data For 18,000 Teachers

I suspect this won't end well:

After a long legal battle and amid much anguish by teachers and other educators, the New York City Education Department released individual performance rankings of 18,000 public school teachers on Friday, while admonishing the news media not to use the scores to label or pillory teachers. 

The reports, which name teachers as well as their schools, rank teachers based on their students' gains on the state's math and English exams over five years and up until the 2009-10 school year. The city released the reports after the United Federation of Teachers exhausted all legal remedies to block their public disclosure. 

At a briefing on Friday morning, an Education Department official said that over the five years, 521 teachers were rated in the bottom 5 percent for two or more years, and 696 were repeatedly in the top 5 percent. But citing both the wide margin of error -- on average, a teacher's math score could be 35 percentage points off, or 53 points on the English exam -- as well as the limited sample size -- some teachers are being judged on as few as 10 students -- city education officials said their confidence in the data varied widely from case to case. 

"The purpose of these reports is not to look at any individual score in isolation ever," said the Education Department's chief academic officer, Shael Polakow-Suransky. "No principal would ever make a decision on this score alone and we would never invite anyone -- parents, reporters, principals, teachers -- to draw a conclusion based on this score alone."

Education isn't my beat--but a 53 point margin of error just seems sprawling. Can some stat heads talk to me like I'm stupid and explain the value of these numbers? Am I missing something?

There's also something unsavory releasing admittedly flawed data, and then lecturing the public on its need to exercise caution.