The wide range of suggested criteria for evaluating teachers has resulted in numerous methods designed to quantify those criteria. The most important characteristic for any successful evaluation method is validity - whether a test or procedure measures what it purports to measure. It becomes inappropriate, meaningless, and useless to make specific inferences from invalid measurements. Evidence of validity must be accumulated to support inferences made from evaluation results. Reliability means consistency - an evaluation always must give similar scores, ranking, or ratings for similiar tests, regardless of the evaluator or the evaluated.
Effectiveness implies that the evaluation provides results in their most useful format.
Summative evaluation yields a teacher performance score or rank that does not have to be interpreted to be used for accountability. Formative evaluation initiates the improvement of weak areas. Efficiency refers to spending time and money for evaluation training, materials, and procedure to ensure the desired results. Present evaluation programs consist of varying combinations of the following components. An updated, formalized version, the Teacher Perceiver Interview, reduces possibe interviewer bias.