Maybe we should call it an “unconfidence interval”
Sharon Otterman wrote over the weekend in the New York Times about the complications of value-added scores for teachers, including teacher-of-record issues and a confidence interval that may give observers more pause than confidence. A commenter to my previous post on teacher-of-record noted the confidence interval issue, which is clearly demarcated in the Times story: A city teacher ranked in the 63rd percentile could actually stand anywhere from 46th to 80th.