I am willing to bet there have been a few people reading this that early in their careers have had a moment of “what does that mean” when learning new procedures and or methods. You are about to learn mine. When I was onboarding and learning new standard operating procedures and methods one really stood out and still does to this day. It was when I was first exposed to EPA method 1664B. It stated right in the introduction it is a performance-based method. I thought to myself what does a performance-based method consist of and how do all labs qualify to run it?