Pedro Arantes
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Goodhart's Law

It stands that a measure ceases to be a good measure when it becomes a target.
#charles-goodhart
Zettelkasten, June 22, 2021
## Notes - It stands that a measure ceases to be a good measure when it becomes a target. - Charles Goodhart advanced this idea in 1975. - When we pick a feature of the economy as an indicator of the economy, it ceases to function as that indicator because people start to game it. - The same happens to statistical variables. - It's a [system mental model](/zettel/system-mental-models) because it explains how a system works when a measure becomes the target. - Using multiples targets avoids Goodhart's Law because you must increase them all, not only one. - If you measure people on the number of nails made, you might get many tiny nails. If you measure the weight of nails made, you might get a few giant and heavy nails. - Educational systems that measure the students by grades incentivize them to memorize content for a test, then promptly forget it all. ## Questions - How do you avoid Goodhart's Law? ## References - [Wikipedia. Goodhart's law](https://en.wikipedia.org/wiki/Goodhart%27s_law) - [Will Koehrsen. Unintended Consequences and Goodhart’s Law](https://towardsdatascience.com/unintended-consequences-and-goodharts-law-68d60a94705c)
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