“You can’t manage what you can’t measure.” is a quality quote often attributed to Peter Drucker the Austrian-born American management consultant, educator, and author.
Peter Drucker may have actually summarised William Thomson, 1st Baron Kelvin (aka Lord Kelvin) much earlier quote which stated:
“When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts advanced to the stage of science.”
Irrespectively, the premise of the quote implies that without a clearly established metric for success, you cannot quantify progress and manage your process to produce the desired outcome. Without clearly defined quality objectives, and a system to measure performance you’re flying blind in a constant state of guessing.