Every quarter the regional office of a bank in Tashkent sends the board a spreadsheet of its branches. Each row shows a branch, its number of employees and its total sales. For years the rows were sorted by branch name, from A to Z, and nobody thought to change it.
This spring the board asked a new question: which branch is the most efficient? The regional manager, Dilshod, looked at the table and named the branch at the top of the sales column. It had sold 900,000 dollars of products, far more than any other.
His assistant, Nargiza, was not so sure. The biggest branch also had the biggest staff: thirty employees. She added one column, sales per employee, and divided each row. The big branch came to 30,000 dollars per person. A small branch in the suburbs, with only twelve employees and 480,000 dollars of sales, came to 40,000 dollars per person.
Then she sorted the whole table by the new column. The order changed completely. The small branch moved from near the bottom of the list to the top, and the famous big branch fell to the middle.
Dilshod changed his report. He explained to the board that "the biggest" and "the most efficient" are different questions, and that a table answers only the question its columns are built for. Total sales measure size; sales per employee measure productivity.
The board asked for the new column to stay. From the next quarter the spreadsheet arrived sorted by sales per employee, with the alphabetical version kept on a second sheet. Nargiza was asked to visit the small branch and write down what its team did differently, so that other branches could copy it.