Five focusing steps
The theory of constraints is based on the premise that the rate of goal achievement by a goal-oriented system (i.e., the system's throughput) is limited by at least one constraint. The argument by reductio ad absurdum is as follows: If there was nothing preventing a system from achieving higher throughput (i.e., more goal units in a unit of time), its throughput would be infinite—which is impossible in a real-life system. Only by increasing flow through the constraint can overall throughput be increased.
Assuming the goal of a system has been articulated and its measurements defined, the steps are:
- Identify the system’s constraint(s)—that which prevents obtaining more of the goal in a unit of time.
- Exploit the system’s constraint(s)—how to get the most out of the constraint.
- Subordinate everything else to the above decision—align the whole system or organization to support the decision made above.
- Elevate the constraint(s)—make other major changes needed to increase the constraint's capacity.
- Repeat—Warning: do not allow inertia to cause a system's constraint.
The goal of a commercial organization is: “Create more value now and in the future”, and its measurements are given by throughput accounting as: throughput, inventory, and operating expenses.
The five focusing steps aim to ensure ongoing improvement efforts are centered on the organization's constraint(s). In the theory of constraints literature, this is referred to as the process of ongoing improvement (POOGI).