LikeLike

]]>LikeLike

]]>Evaluating New York Teachers, Perhaps the Numbers Do Lie

http://www.nytimes.com/2011/03/07/education/07winerip.html?_r=1

he calculation for Ms. Isaacson’s 3.69 predicted score is even more daunting. It is based on 32 variables — including whether a student was “retained in grade before pretest year” and whether a student is “new to city in pretest or post-test year.”

Those 32 variables are plugged into a statistical model that looks like one of those equations that in “Good Will Hunting” only Matt Damon was capable of solving.

The process appears transparent, but it is clear as mud, even for smart lay people like teachers, principals and — I hesitate to say this — journalists.Ms. Isaacson may have two Ivy League degrees, but she is lost. “I find this impossible to understand,” she said.

In plain English, Ms. Isaacson’s best guess about what the department is trying to tell her is: Even though 65 of her 66 students scored proficient on the state test, more of her 3s should have been 4s.

But that is only a guess.

Moreover, as the city indicates on the data reports,

there is a large margin of error.So Ms. Isaacson’s 7th percentile could actually be as low as zero or as high as the 52nd percentile — a score that could have earned her tenure.

LikeLike

]]>Isolation feeds her insight.

LikeLike

]]>Euler, or, Ferris Bueller?

LikeLike

]]>Thanks for the additional information. When and if they finally release a technical paper, it will have been about two full years since the plan was implemented and teachers have been deemed effective or otherwise, based on a secret black box that no one is allowed to see the contents of. Would teachers ever be permitted to grade our own students, for years, based on an algorithm whose details was held secret from the students and parents? I don’t think so.

LikeLike

]]>In addition to revealing the coefficients of the regression, they should reveal its fit (R^2) and summary statistics about the population (mean, standard deviation of each of the variables). That would be de rigeur for publishing in any peer-reviewed journal.

LikeLike

]]>Many of the variables you speak of are “yes-no” type variables. How exactly do you use those to apply some sort of regression?

On Sat, Mar 5, 2011 at 5:53 PM, Guy Brandenburg wrote: > No, I posted the ENTIRE document. They reveal NOTHING. >

LikeLike

]]>No, I posted the ENTIRE document. They reveal NOTHING.

LikeLike

]]>I agree that they absolutely should reveal what the coefficients are. Maybe they do elsewhere in the document — you haven’t posted the whole thing. The values of the variables obviously vary by student and school. Free lunch eligibility, language proficiency, learning disability — I assume that those are relatively well-defined within DCPS. Mathematica got their data from somewhere. You don’t know those variables for each kid in your classroom?

Again, the dimensionality of the error term is the same as that of the dependent variable. When you are running a linear regression on a single dependent variable it makes no sense to refer to a vector of error terms.

LikeLike

]]>