Goodhart's Law
Just as holding an ice pack to a thermometer won't cure a fever, turning a metric into a target destroys its ability to measure real health.
Definition Goodhart's Law is an economic rule stating that when a measure becomes a target, it ceases to be a good measure. Once people are evaluated on a specific metric, they change their behavior to optimize that number, causing the metric to lose its connection to the actual value it was meant to reflect. It was first introduced by British economist Charles Goodhart while analyzing monetary policy.
The Curious Case of the Rushed Call Center
Imagine a company tries to boost call center efficiency by setting a strict goal: keep average call times under three minutes. The original intention was goodโreduce customer wait times and improve satisfaction.
However, the metric led to unintended consequences. When faced with complex or difficult questions, representatives began rushing customers off the phone or hanging up prematurely. Call times dropped dramatically on paper, but customer dissatisfaction skyrocketed. The true objectiveโcustomer satisfactionโwas lost, leaving behind only a game of hitting numerical targets.
When people are evaluated and rewarded based on a single metric, they change their behavior to optimize for that number in the easiest way possible. In the process, the original purpose gets completely sidelined.
A Closer Look: The Monetary Policy Dilemma
This concept was first formulated in 1975 by Charles Goodhart, an advisor to the Bank of England, as a critique of monetary policy. At the time, the British government tried to curb inflation by targeting specific measures of the money supply.
As soon as the government began regulating that particular metric, financial institutions invented new financial instruments to bypass the rules. On paper, the official money supply looked stable, but unregulated money continued to circulate, and inflation kept climbing. The moment the indicator became an artificial target, the statistical relationship between the metric and economic reality collapsed.
People are smart and respond rationally to new rules. When policy changes, people adapt to protect their interests, causing policies based purely on past data to fail.
Why Obsessing Over Numbers Backfires
We often use simple numbers to understand a complex world. We track student learning through test scores and measure researchers by how many papers they publish. Observing trends through numbers isn't inherently bad.
The real trouble begins when these metrics are tied to high-stakes rewards like promotions, bonuses, or penalties. If scientists are judged solely on paper count, they might split one meaningful study into several thin papers. This triggers a reversal of means and ends, prioritizing vanity metrics over real substance.
To overcome Goodhart's Law, organizations must avoid relying on a single metric. Combining quantitative data with qualitative insights and staying flexible is essential to keeping real goals in focus.
๐ค Common misconceptions
Goodhart's Law means metrics and statistics are completely useless.
Metrics themselves are not bad. The problem arises when a metric becomes a target tied to incentives, distorting human behavior. Purely observational metrics remain extremely valuable for understanding trends.
๐งบ Where you meet it
When a measure becomes a target for control or compensation, people game the system, and the metric loses its original value.