In a recent article in the Sunday Los Angeles Times ("Just rewards for teachers," October 2), Marcus Winter acknowledges that basing teacher quality on student gains on standardized tests, known as value-added ratings, is "far from perfect and thus should not be used in isolation …".
Value-added ratings are indeed far from perfect: Different tests produce different value-added ratings, and teachers' value-added ratings can vary from year to year, sometimes quite a bit. In fact, many experts say ratings based on test score gains are so imperfect that they shouldn't be used at all.
Winters claims, however, that teacher experience and credentials should not be considered when determining teacher compensation because his study showed that they were not related to value-added ratings.
His conclusions are far from perfect.
Original article at: http://www.latimes.com/news/opinion/commentary/la-oe-winters-teachers-pay-20111002,0,577207.story