THE IDEA
When the measure becomes the mission
A proxy measure is a stand-in for something you care about. A surrogate measure is what that proxy becomes when everyone forgets it was ever a stand-in. The original goal fades from view. The measure that was supposed to represent it takes its place. And nobody remembers the difference.
This is subtler than Goodhart’s Law, which describes the gaming of a targeted measure. Surrogate measures aren’t necessarily gamed. They’re worse: they’re believed. The organisation genuinely starts to think that the surrogate IS the goal. Maximise shareholder value becomes the purpose of the company, when it was originally a proxy for long-term health. Raise test scores becomes the mission of the school, when it was originally a proxy for learning. Increase engagement becomes the goal of the platform, when it was originally a proxy for user satisfaction.
The displacement is gradual. The measure is introduced as an indicator. It becomes a target. The target becomes a goal. The goal becomes an identity. By the time the process is complete, questioning the measure feels like questioning the mission itself. Anyone who says “but is this actually measuring what we care about?” sounds like they’re attacking the institution’s purpose, when they’re doing the opposite - trying to recover it.
IN PRACTICE
The stand-in that stole the show
GDP was developed as a measure of economic activity - a proxy for national prosperity. Over decades, maximising GDP became the goal of economic policy. Policies are evaluated by their effect on GDP. Countries are ranked by GDP. Growth in GDP is treated as proof that things are getting better. But GDP doesn’t measure wellbeing, environmental health, inequality, community strength, or any number of things that constitute prosperity. The surrogate became the goal, and the actual goal - a good life for citizens - was displaced.
A research institution measures its impact by citation counts. Originally, citations were a useful proxy for whether research was being read and used. Over time, the institution reorganised itself to maximise citations: hiring researchers with high h-indices, prioritising journals with high impact factors, discouraging risky research that might not be cited. The surrogate (citations) displaced the goal (impactful research). The institution is now excellent at producing cited papers and no longer asks whether the papers change anything.
A person measures their fitness by the number on the scale. Weight was a proxy for health. Over time, the number becomes the goal. They skip meals to see a lower number. They feel bad after a large meal because of the number, not because of how they feel. They choose exercise based on calorie burn rather than enjoyment or health benefit. The surrogate has displaced the goal. They’re optimising for the number while the thing the number was supposed to represent - health - goes unattended.
WORKING WITH THIS
Recovering the real goal
The antidote is regularly asking: what was this measure supposed to tell us? What did we actually care about before we had this number? If the measure disappeared tomorrow, would we know what to care about, or would we be lost?
When you notice that the organisation’s energy is focused on improving a measure rather than on the thing the measure represents, sound the alarm. The displacement has happened. The recovery requires going back to first principles: what do we actually want? What does success look like in terms of real impact, not in terms of numbers on a dashboard?
Build periodic “measure audits” into your practice. Every year, for every key metric, ask: does this still represent what we care about? Has the link between the measure and the goal weakened? If we’re improving this number, is the actual situation improving? These questions are uncomfortable because they sometimes reveal that the organisation has been optimising the wrong thing. But that discomfort is the price of staying connected to the mission, rather than to the number that was supposed to serve it.
THE INSIGHT
The line to remember
The most dangerous measure isn’t the one that’s wrong. It’s the one that was right once, became the goal, and is now taken for granted - long after the thing it measured and the thing that matters have parted company.
RECOGNITION
When this is in play
You’re dealing with a surrogate measure when nobody can remember what the metric was originally supposed to represent. When the question “why do we measure this?” produces the answer “because it’s what we measure.” When improving the number has become the purpose, not a signal of progress toward a different purpose. When someone suggests a different way of measuring success and is met with incomprehension rather than curiosity. When the metric and the mission have become the same word.