To measure is to know..
Control is everything, it allows processes to operate, to successfully produce products or to provide a service which potentially aids the environment, makes a product or services a market. So when a process or plant is running, is it running well? Well, how well? Can it be better? Can it be more efficient? Safer? Cheaper? Well yes, the question is by how much?
These questions can be general at times and effort needs to determine by how much and what is the over aching objective of the effort. For without this there will never be a clear measure of success and completion of a project, and more importantly something to measure.