Continual improvement is a key element of SPC and total quality. SPC enhances the predictability of processes and whole plants. Elimination of waste is another key element of SPC. SPC can help improve product quality, while reducing product cost. The steps in developing a control chart are as follows: 

(a) determine sampling procedure, 

(b) collect initial data of 100 or more individual points, 

(c) calculate the mean values of the data in each subgroup, 

(d) calculate the data range for each subgroup, 

(e) calculate the average of the subgroup averages, 

(f) calculate the average of the subgroup ranges, 

(g) calculate the process upper and lower limits, 

(h) draw the control chart, and 

(i) plot the data on the chart. Management’s role in SPC is similar to its role in total quality overall: commitment, the provision of training, and involvement. The seven tools, augmented by flowcharting, Five-S, FMEA, and DOE, may be used with SPC. SPC and the operator must have process-stop authority. SPC implementation must be carried out in an orderly, well-thought-out sequence. The quality tools are used in SPC before the control chart is developed as aids in helping to eliminate special causes of variability.