The Subtotal Button — What a Supermarket Checkout Taught Me About Metrics
In the summer of 1996, I discovered a button that paused the performance clock. Within weeks I was the fastest checkout operator in the West of Sheffield, then the company. Productivity, according to the numbers, had exploded. Cash in the bank had not.
Originally published 2017 · Updated April 2026
In the summer of 1996, during the great Britpop heatwave, I was working on the checkouts of a supermarket in Sheffield.
I was seventeen. Permanently tired. Mildly sunburnt. With long hair. And deeply bored.
One afternoon, hiding in the basement canteen from the heat, I noticed a thick manual – wedged beside the coffee machine. It was the operating guide for our checkout system.
There was nothing else to do. So I read it.
On page seventy-five I found a sentence that would quietly shape how I think about organisations to this day:
Pressing the subtotal button suspends all timing functions.
In plain English: hit “subtotal” and the performance-clock stops.
This mattered because the only thing my managers measured was speed.
How fast could I scan shopping through the checkout?
Speed, we were told, was productivity.
Productivity was profit.
Simple.
Except it wasn’t.
Editor's note — where this sits
This essay uses a personal story to illuminate one of the central problems in organisational life — the gap between what we measure and what we actually value. It sits in the Physics layer of the Idea to Value system — the layer concerned with how ideas move toward real outcomes, and how that movement gets distorted when measures point in the wrong direction. It also connects to the Map layer: what we're pointed toward determines everything that follows.
The Idea to Value system — five layers
What the System Rewarded
I had never been the fastest operator.
Not because I was lazy, but because I cared.
In this store we packed bags for customers. I spoke to people. I waited when they were flustered. I treated them like human beings rather than items in a queue.
Customers chose my line. My feedback score was high. I got to know our customers.
Management told me I was too slow.
The system had decided what “good work” meant.
And it wasn’t the same thing most customers valued.
Gaming the Measure
Once I discovered the subtotal button, everything changed.
I could pause the clock during delays.
Spillages. Waiting for approval. Customers still unloading trolleys. Helping someone pack carefully.
I could now deliver good service and still appear lightning fast.
Within weeks I was crowned the fastest checkout operator in the store.
Then the West of Sheffield.
Then the company.
Productivity, according to the numbers, had exploded.
Cash in the bank had not.
The system was lying to itself.
What I Had Really Discovered
I hadn’t improved productivity.
I had exposed a flaw in how it was defined.
The organisation had confused:
Speed with value.
They were measuring activity, not outcome.
This is the hidden danger of crude metrics.
When a single number becomes sacred, it stops revealing reality and starts distorting it.
Good people adapt to survive inside bad measurement systems.
Not because they are unethical, but because they are human.
Speed Is Not the Same as Value
You can move quickly and still move badly.
You can ship poor work faster.
You can rush customers through unhappy experiences.
You can increase throughput while degrading quality.
Speed is easy.
Meaningful productivity towards value is not.
True productivity is not about motion.
It is about flow.
Smooth processes towards real value.
You must first understand the system before you can improve it.
What Metrics Really Do
Measures are not neutral.
They shape behaviour.
They quietly tell people what matters, regardless of what leaders say.
If you measure speed alone, you train people to prioritise speed over care.
If you measure volume alone, you train people to prioritise output over quality.
People stop working to what the company values, and the value it generates.
They work to measures.
Why Good People Break Bad Systems
Most gaming of metrics is not malice.
It is adaptation.
When people are punished for doing the right thing, they will eventually stop doing it.
Fear distorts behaviour faster than policy ever could.
Systems that mis-measure reality slowly teach their people to misrepresent it.
The Real Lesson
What I learned on a supermarket checkout has repeated itself throughout my career.
In every industry, the same pattern appears:
Organisations mistake what is easy to count for what truly counts.
They optimise numbers instead of experience.
They manage symbols instead of systems.
And then they are surprised when behaviour drifts away from their intentions.
When the Measure Becomes the Problem
The moment a metric stops being a window and becomes a target, it stops telling the truth.
Good measures illuminate work.
Bad measures replace it.
If you want better performance, begin by studying what is really happening. And orientate around value.
Not just the numbers.
The system.
Because when you misunderstand value, you do not merely mismanage work.
You mis-shape human behaviour.
And quietly, without realising it, you train good people to do the wrong thing well.
Idea → Value System
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A practical system for seeing how ideas actually move toward value — and where measures, priorities, and activity sets can distort that movement before anyone notices.
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Explore the system →The 10 Behaviours of Effective Employees
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When measures are wrong, behaviour drifts. A shared language for the everyday behaviours that actually create trust, quality, and value — regardless of what the numbers say.
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