Why the worker is unmeasured
Every machine on the line has a meter. Every kilowatt-hour, every kilogram of solder paste, every cycle of a pick-and-place head — counted, logged, traceable. The worker is the only input on the floor that the MES has nothing to say about. The supervisor knows there is a 20-40% output gap between best and worst on the same line, same shift. The supervisor cannot point at a number to explain it. Roughly a fifth of real work time is not recorded by any system at all. The variable is loud, and the instrument does not exist.