A system is a collection of parts, which are interdependent and should work together to accomplish some aim.
A system must have an aim or purpose.
Telephone engineers are told they need to do 3.2 jobs per man per day. Is that the aim of the system?
The target ‘part’ of this system will govern the behaviour of the engineer and will work against the system’s purpose.
The engineer rightly thinks his purpose to be conduct effective repairs, repairs that solve customers’ problems and that ensure he has no need to return.
But his manager believes making that the focus will drive costs up. He’s wrong about that, but it is the way he has been taught to think: activity = cost.
Having studied the system, the engineer believes ‘perfect’ would be having no repairs to do. Instead of working in a ‘break-fix’ system, he now thinks he should work in a ‘preventative’ system, one where the number of faults being reported falls.
Each of these three systems (3.2 jobs per day, perfect repairs and preventing repairs) will have different measures, based on different assumptions and will, therefore, behave have differently.
A system must be managed, it will not manage itself. By understanding the system one will be able to predict the consequences of a proposed course of action.