The first point I want to make is that any measure has flaws and will not completely reflect reality. They should be considered indicators and in some way all refer to some sort of “standard” or desired condition. This is the basis for problem identification, which is the main purpose.
Any measure is a “snapshot” of conditions during a specific time period and reflects many variables that are occurring. Some measures such as productivity are based on assumptions such as standard hours. The notion of standard hours is flawed in many ways that I won’t get into, but this measure can be used effectively (if used carefully). The mistake that is often made is to evaluate performance based on the measure and to drive inappropriate behaviors like overproduction.
Insights on productivity metrics used at Toyota.
See on theleanedge.org