There are requirements. When determining the control limit, use the limited batch of measurement data, the requirements for measurement value control chart and count value control chart. Defect rate control chart (PCchart) defect numerical control chart (nPchart, also known as npchart or DCchart) defect numerical control chart (Cchart) unit defect numerical control chart (Uchart)2. Control chart for classification and analysis according to the purpose of control chart.