What does it mean to have a valid and reliable measure of effective teaching?
To ensure that an effectiveness measure is valid and reliable, the results of the measure are compared to: 1) actual student outcomes, to determine how well the measure predicts student outcomes (validity), and 2) results of the same measure used to evaluate the same teacher and lesson but applied by a different rater, to determine how consistent the measure is when used by different people (reliability). For example, to prove the validity and reliability of an observation rubric, scores assigned by a group of raters using the rubric would be compared to actual student achievement gains in the observed classroom and to scores assigned by a different group of raters to the same classroom and lesson.
