How has increased educator accountability helped to improve education at the school level?

Educator Accountability

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Book: Chapter 5-6
Fowler, F. C. (2013). Policy studies for educational leaders: An introduction (4th ed.). Boston, MA: Allyn & Bacon

Although educator accountability is not a new concept, it has become more deliberate and public in recent years. How has increased educator accountability helped to improve education at the school level? How has it been detrimental to education?