There is a special kind of intelligence that only appears at the supermarket checkout.
SHORT STORIES
There is a special kind of intelligence that only appears at the supermarket checkout.
You have been standing in the same line for three minutes.
Nothing moves.
The line next to you?
Beautiful.
One customer leaves. Then another.
You begin collecting data.
Four people ahead of me.
Three over there.
My carts look bigger.
Their cashier looks faster.
You perform a complete capacity analysis based on approximately twelve seconds of observation.
The conclusion is obvious.
Move.
So you move.
And immediately, the person in front of you needs a price check.
Then a card doesn’t work.
Then someone decides this is the perfect moment to ask about the store’s loyalty program.
Meanwhile, your old line begins moving with the efficiency of a Toyota assembly line.
Of course.
It feels like bad luck.
But queueing theory offers a less personal explanation.
Two lines with the same number of people can have very different waiting times. Service times vary. One large cart, one price check, one payment problem can change the behavior of the entire queue.
And we cannot see most of that when we make our decision.
We change lines because we can see the queue.
We cannot see the variability.
We do something very similar at work.
A metric turns red.
A process slows down.
A delivery is late.
We see the signal and feel the urge to move.
Change the priority.
Move the people.
Add another control.
Call another meeting.
Sometimes that is exactly what the system needs.
Sometimes we are just changing checkout lines.
The problem is not acting.
The problem is acting as if the few moments we observed explained the system.
Seeing the queue is easy.
Learning to see the variability takes a little longer.