Statistical process control (SPC) is a statistical based approach that monitors long-term process performance. It is used to identify and remove causes of process disturbances. Automatic process control (APC) is an engineering based approach that monitors processes and provides short-term adjustments. It is used to continually compensate for process disturbances. This paper focuses on control systems that combine these two approaches and may provide improved process performance when compared with either approach. The objective is to investigate the conditions at which SPC or APC or both are applicable as well as the control limits that minimize the total quality loss.