What is the nature of your industry? What is your finished product?
To decide the work efficiency, you need to study the systems and processes of each department. Thereafter, you need to identify various costs or ratios associated with each department. Efficiency is monitored based on these ratios or costs.
While this formula works well in most of the departments, it may not work well for departments like Admin, Legal etc.
It appears that you have not instituted well-defined and well-researched Performance Management System in your company. As of now, how do you measure the performance of each department? If you wish to have a paid consulting service, then feel free to contact me. You may click here to download my contact details.
From India, Bangalore