It’s usually not a good idea to rely solely on a single statistic to draw conclusions about your process. Do that, and you could fall into the clutches of the “duck-rabbit” illusion shown below.

It is vitally important for lean people to know nothing when working on improvement. This sounds like a crazy idea, but it is another 100-percent turnaround from traditional management thinking.

What comes to mind when you think of “return on investment?” For most of us, our mind jumps to calculations of costs and revenues. The end goal, no matter the project, is for the last cell in the spreadsheet to be black or green—not red.