30 April, 2010

Goodhart goes to school

Are you familiar with Goodhart's law?
No, not Godwin's Law of NAZI analogies. While that may have some impact on your school or library (teaching kids how to debate or write signs for a teabagger rally), Goodhart's law is the one I was wanting to think about today.

Goodhart came up with his law during the Thatcher years in Britain and it related to monetary policy. In brief it suggests that measuring something changes it (yes, that is similar to Heisenberg's uncertainty principle but that is quantum theory and I don't usually like the idea of assuming that what is true of waveforms is a universal truth to live my life by). But Goodhart goes further than that, to suggest that in finance or social policy the change makes the measuring unsuitable for its original purpose.

A government decides to test all students nationwide to determine how well students are reaching certain educational markers (good idea).
but then...

Private schools work out that they can use a bit of game theory and teach specifically to the test. Thus improving their appearance of success (but not necessarily improving real world outcomes for their students).

So, our public schools follow suit (teaching to the test). Private schools must then raise their performance again, so poorly performing students are jettisoned before the testing date or given a convenient diagnosis of ADHD or dyslexia to allow them extra time on the test.

Before you know it you have a test which measures nothing more than the ability of teachers and administrators to play the system.

As you may gather, I see very little of benefit in the information I as a parent can gain from the my school website that our wonderful Labour government has set up. It shows almost nothing which will allow me to work out how my child will perform in a particular school. Not to mention, if I am sending my kids to a public school, I have very little choice where they will attend (the nearest one is usually the rule). So, if I am well off (or willing to make sacrifices) I can send my kids to a private school. But if I am well off I am probably living in a good socio economic area and as such will be close to a well performing school.

This is old news I know. But the complete stupidity of thinking that you can measure the ability of teachers through standardised testing performed every few years is insane and it is about to happen again. Except, it seems a lot of teachers are now willing to take a stand and are refusing to administer the test.

Damn, I have come to the end of my post and have reached no conclusion.

Goodhart's law makes sense to me. There, done.

No comments: