Yield
The share of pieces that survive a process, which multiplies down a routing rather than adding, so 7 good operations still lose more than you expect.
Yield is the complement of scrap and it behaves in a way that surprises people the first time they work it out. Seven operations each running at 98 percent do not produce a 98 percent routing. They produce 0.98 to the power of 7, which is 86.8 percent, so 13 pieces in every 100 started never ship.
That compounding is why delivering 1,000 good pieces means starting 1,152, and why the material line, the machine hours and the inspection time all have to be quoted against the started quantity rather than the shipped one.
The same effect runs across assembly levels rather than operations. Three levels at 98 percent each is 94.1 percent at the top, and the losses are weighted toward the expensive end because a unit scrapped at final test carries everything underneath it.
Cumulative yield is also the number that decides whether a process is quotable at all. A routing where the honest cumulative figure sits below 80 percent is telling you something about capability that no price adjustment fixes, and it belongs in the conversation before the quote goes out rather than in the variance report afterwards.