Too Much Efficiency Makes Everything Worse: Overfitting and the Strong Version of Goodhart's Law

Increased efficiency can sometimes, counterintuitively, lead to worse outcomes. This is true almost everywhere.

Increasing efficiency is permeating almost every aspect of our society. If the thing that is being made more efficient is beneficial, then the increased efficiency makes the world a better place (overall, the world seems to be becoming a better place). If the thing that is being made more efficient is socially harmful, then the consequences of grea... See more

Increased efficiency can sometimes, counterintuitively, lead to worse outcomes. This is true almost everywhere. We will name this phenomenon the strong version of Goodhart's law. As one example, more efficient centralized tracking of student progress by standardized testing seems like such a good idea that well-intentioned laws manda

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Goodhart's law states that,  when a measure becomes a target, it ceases to be a good measure 2 . Goodhart proposed this in the context of monetary policy, but it applies far more broadly. In the context of overfitting in machine learning, it describes how the proxy objective we optimize ceases to be a good measure of the object

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