When a measure becomes a target, it ceases to be a good measure.
Goodhart's original 1975 form was that an observed statistical regularity tends to collapse once pressure is placed on it for control, stated about monetary aggregates: as soon as the Bank targeted a measure of money supply, the relationship it had relied on broke down. The familiar wording is Strathern's 1997 generalisation.
In practice
- A support team measured on average handling time closes conversations before the problem is solved.
- A hospital measured on ambulance handover times holds patients in the ambulance, and the measure improves.
- Standing
- The Chinese administrative idiom shang you zhengce, xia you duice states the implementation half of the same mechanism.
- Further reading
- Wikipedia
- Subject
- Economics & Incentives
- Essay
- The regularities money obeys