Introduction

“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.” —Lord Kelvin

Metrics are a commonly-used tool to help gauge the performance of a team, and are frequently the tool of choice for engineering managers who are first looking for clear, objective(-ish) ways to judge the performance of an individual or a team. However, as with most tools in software development, over-reliance on metrics can have the exact opposite effect than desired, and in many cases can lead to the very undesired behavior they were trying to protect against.