Goodhart's Law

Named after the economist Charles Goodhart, the principle states,

When a measure becomes a target, it ceases to be a good measure.

Also known as the Cobra Effect

The Laws of human nature

In nineteenth-century India, under British colonial rule, authorities decided there were too many venomous cobras in the streets of Delhi, making life uncomfortable for the British residents and their families. To solve this they offered a reward for every dead cobra residents would bring in. Soon enterprising locals began to breed cobras in order to make a living from the bounty. The government caught on to this and canceled the program. The breeders, resentful of the rulers and angered by their actions, decided to release their cobras back on the streets, thereby tripling the population from before the government program.

Atomic Habits

We care more about getting ten thousand steps than we do about being healthy. We teach for standardized tests instead of emphasizing learning, curiosity, and critical thinking. In short, we optimize for what we measure. When we choose the wrong measurement, we get the wrong behavior…. … Measurement is only useful when it guides you and adds context to a larger picture, not when it consumes you. Each number is simply one piece of feedback in the overall system. In our data-driven world, we tend to overvalue numbers and undervalue anything ephemeral, soft, and difficult to quantify. We mistakenly think the factors we can measure are the only factors that exist. But just because you can measure something doesn’t mean it’s the most important thing. And just because you can’t measure something doesn’t mean it’s not important at all.

How to Make the World Add Up - RULE TWO, Ponder your personal experience

There was the time the UK government collected data on how many days people had to wait for an appointment when they called their doctor, which is a useful thing to know. But then the government set a target to reduce the average waiting time. Doctors logically responded by refusing to take any advance bookings at all; patients had to phone up every morning and hope they happened to be among the first to get through. Waiting times became, by definition, always less than a day.

Then there is the notorious obsession with the ‘body count’ metric, which was embraced by US Defense Secretary Robert McNamara during the Vietnam War. The more of the enemy you kill, reasoned McNamara, the closer you are to winning. This was always a dubious idea, but the body count quickly became an informal metric for ranking units and handing out promotions, and was therefore often exaggerated. And since it was sometimes easier to count enemies who were already dead than to kill anyone new, counting bodies became a military objective in itself.

Social scientists have long understood that statistical metrics are at their most pernicious when they are being used to control the world, rather than try to understand it. Economists tend to cite their colleague Charles Goodhart, who wrote in 1975: ‘Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes’