Freakonomics and Marginal Revolution face off on unintended consequences - it’s timely food for thought about the potential consequences of adopting value-added as the primary measure of teacher effectiveness. As I’ve noted before, value-added as one of many measures works for me; value-added as the master measure - which I fear it would become - does not. Why? Teaching is a multifaceted task, and value-added measures use a simplistic evaluation rubric to monitor a complex task. Alex Tabarrok sums up the potential problem here:
The law of unintended consequences is what happens when a simple system tries to regulate a complex system. The political system is simple, it operates with limited information (rational ignorance), short time horizons, low feedback, and poor and misaligned incentives. Society in contrast is a complex, evolving, high-feedback, incentive-driven system. When a simple system tries to regulate a complex system you often get unintended consequences.
An unintended consequence of blogging is that I am about to miss a deadline, so I’ve got to bounce. Stay tuned for more value-added debate next week. Enjoy the weekend, everyone!
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