可以理解为单位产出，不仅是指人均的，考虑技术进步时候还要除掉技术，考虑土地因素时候要除掉土地。

efficiency unit： Output per worker per hour  每个工人每个小时的产出

Definition of Efficiency Units: Efficiency units are usually interpretable as "output per worker per hour."

More generally: An abstract measure of the amount produced for a constant production technology by a worker in some time period. Often the context is theoretical and the time period and production technology do not have to be specified. But efficiency units can be conceived of (and theorized about) as a function of each worker's characteristics, of the vintage of equipment, of the date in history, of the production technology, and so forth.