- VAMs are generally based on standardized test scores, and do not directly measure potential teacher contributions toward other student outcomes.
- VAMs typically measure correlation, not causation: Effects – positive or negative – attributed to a teacher may actually be caused by other factors that are not captured in the model.
**Update: After writing and posting this entry, I learned that Tennessee's governor signed legislation prohibiting teacher evaluations based on VAMs. Diane Ravitch has the breaking news.
Then I saw a post indicating Washington state has lost its NCLB wavier because it has not tied teacher evaluations to metrics, such as VAMs. This, of course, is Arne Duncan's doing. He continues to show his utter disdain for teachers. See this for more.