Cobra Effect · Start here
What you measure is what you get
Why the number you chase quietly replaces the thing you wanted.
6 cards, read aloud in 1:57, with a test and sources.
You want a better life. So you pick a number.
Income is the obvious one. It is easy to measure, it moves when you push it, and nobody argues that it matters. So it quietly becomes the goal.
Ten years later, the number is up.
Longer hours. A bigger mortgage. Less time with the people the money was for. The number did exactly what you asked. The life it was standing in for did not.
There is an old story about this, with snakes in it.
A city, so the tale goes, paid a bounty for every dead cobra. People bred cobras to collect it. When the bounty stopped, they let the snakes go, and the city had more cobras than before. You get what you measure. Exactly what you measure.
This is the one idea underneath most of the others.
A proxy is a number that stands in for something you cannot count directly. Proxies are useful right up until you start optimising them. Then they stop measuring the thing and start replacing it.
Every story here is a version of it.
Measuring the wrong sample. Measuring what you spent instead of what is left. Measuring noise and calling it progress. And a few rare cases where the number and the goal actually agree. Those are the ones worth building a life on.
So here is the promise, and the question.
Nothing here will reward you for showing up. Streaks and minutes are proxies too. The only thing that counts is whether you can use the idea when it matters. So carry one question out with you. What am I actually measuring, and what did I want?
Sources
- Campbell’s law, Donald Campbell, 1976. The social-policy version of the thesis: the more a number is used to decide things, the more it will be corrupted. Wikipedia has the quote and the paper reference.
- The Tyranny of Metrics, Jerry Muller, 2018. A whole book of cobra farms: medicine, schools, policing, universities. Short, angry, well sourced.
- Goodhart’s law and its cousins, Wikipedia. The map of the whole family, with the differences between them spelled out.
Nearby ideas
- The Cobra effect. Why paying for a result can breed more of the problem.
- Goodhart’s law. A measure turned into a target stops telling you the truth.
- Second order effects. Every fix has consequences, and those have consequences too.