In 2016, a European gas-station chain hired HappyOrNot, a small Finnish startup, to measure customer satisfaction at its hundred and fifty-plus outlets. One gas station rapidly emerged as the leader, and another as the distant laggard. But customer satisfaction can be influenced by factors unrelated to customer service, so, to check, the chain’s executives swapped the managers at the best and worst performers. Within a short time, the store at the top of the original list was at the bottom, the store at the bottom was at the top, and one of the managers was looking for work.

David Owen, Customer Satisfaction at the Push of a Button, The New Yorker February 5, 2018