In A Nutshell

The drive for empirically-based improvement is also the drive for a quantitative understanding of our performance.

 
...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...
— Lord Kelvin (William Thomson)

Empiricism is, therefore, the foundation of our Inspect and Adapt behaviours at all levels. It leads us to seek an understanding of our current performance so that we can identify problems and blocks that are limiting that performance. Accurate identification of problems and blocks requires a quantitative analysis of our performance.