Cat HicksDec 15

"Goodhart’s Law is really a statement about the process of trying to make policy based on proxy measures of “internal states of complex systems” which are not themselves directly observable. "

Got to this piece from a link from Ben Recht and it finally nailed something that's always bothered me about the constant reference to Goodhart's law across software.

https://backofmind.substack.com/p/goodhart-as-epistemologist

goodhart as epistemologist

what did that "law" really say?

Dan Davies - "Back of Mind"
Show threadCat HicksDec 15

First of all I actually think people usually mean to reference behavioral incentive change, in which case you should say Campbell's Law probably; second of all neither of these "laws" ever meant that measurement can't be meaningful

"So the message of Goodhart’s Law is that if you’re setting targets, they ought to target the thing that you care about, not something which you believe to be related to it, no matter how much easier that intermediate thing is to measure."

Show threadCat HicksDec 15

Of course, many people come to these conversations so convinced that no shared meaningful measurement is ever possible, they would prefer to say: all measures are always going to be subject to goodhart's law

I don't believe that, though. I think for most of us, if you're going to take a medicine you will want to know how many people were helped or died after that medicine was administered. Measurement is necessary. I do understand we may have reasonable disagreements about the when and how

Show threadCat HicksDec 15

I explicitly think that we should take seriously the way that measurement operates as a social lever and USE THAT

This is not remotely controversial if you're someone who's worked in policy. Here is an example:

https://www.urban.org/policy-centers/cross-center-initiatives/kids-context/projects/kids-share-analyzing-federal

Show threadCat Hicks
"Children can’t vote and they can’t lobby for public resources, but their well-being and development affect the future economic and social health of the country. Children also can’t work their way out of poverty, so the government has a special calling to protect them."
Dec 15 at 6:11pmWeb
Show threadCat HicksDec 15

"Public investments are used to educate children; promote their health, safety, and well-being; ensure their basic needs are met; and help protect their families from financial hardship. These investments come in the form of direct spending on programs that serve kids and through tax benefits that offer their families financial assistance.

Determining how government spends money, and who benefits, reveals our priorities."

And quant is part of this work.

Show threadtwifkakDec 15
@grimalkina I agree that output metrics can be useful, either as inputs to a decision tree or as incentive levers. I always used Goodhart's law as a warning against overfitting. Also as a humorous exaggeration, in a similar vein as the https://en.wikipedia.org/wiki/Ninety%E2%80%93ninety_rule. Is that not correct? Is that not how others use it?
Ninety–ninety rule - Wikipedia