Three major Statistical Quality Control (SQC) tools are Experimental Design, Statistical Process Control (SPC) and Acceptance Sampling. Experimental Design and SPC take about 80% of the SQC activities, and Acceptance Sampling is not necessary if the two tools have been implemented appropriately.
Experimental Design is an off-line tool whereas SPC is an on-line one. The typical example of the SPC is the control chart which is designed to monitor the occurrence of the assignable cause in the process.
In this talk, 4W (When, Who, What, Why) and 1H (How) of the control chart technique will be explained briefly. Especially, three major types of control charts are introduced and compared each other in terms of the efficiency. The current issues of the control chart are also explained.