Saturday, September 04, 2010

Klein: Better One or Better Two?

Ezra Klein has found a great metaphor for how we should think about politics: the eye exam. Anyone unfortunate enough to have to be fitted with glasses knows the routine: after trying to read the eye chart without glasses, and misreading the "E" as "P", the optometrist inserts a lens in front of your eye, has you read down some lines, then starts the comparison routine, quickly switching between two lenses and asking: "better one or better two?" [Note: Klein uses the ophthalmologist, but optometrist is easier to spell.]

That's mostly how we need to think about many political and social issues.  For example, evaluating teachers.  Is it better not to evaluate or to evaluate by having the principal monitor the class a couple times a year?  Is looking at class test scores better than principal monitoring, or worse?  Is a combo of test scores and monitoring better than either alone.  Is looking at "value-added" scores better than raw scores?  etc. etc.

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