Most discussions of measures
of teacher performance measures focus on validity and reliability; but fairness, simplicity, and cost should also be considered.
As a result, schools and districts around the country are now experimenting with a wide range of policies to
improve teacher performance measures and use these to make high - stakes decisions such as dismissing low - performing teachers.
Opting out adds noise to the data, which increases the amount of variability in
the teacher performance measures because each teacher's score is based on fewer students.