The Shewhart’s control charts

which were first introduced in 1924

can be used to distinguish between product-quality variations caused by chance and assignable causes. But there is a more general process

in which it is necessary to further divide the assignable causes into those we are interested and those we are not

and then select out the former and exert control over them. However

the Shewhart’s control charts cannot distinguish between these two classes of assignable causes.A new type of control charts called selecting control charts is given in the present paper

which can give alarm only to the assignable causes we are interested and neglect those we are not interested.The idea of selecting control charts is fundamentally different from that of the Shewhart’s ones

the former can distinguish one more class of assignable causes than the latter.The selecting control charts have succeeded in controlling the overlimit rate and the register-return rate of long-distance calls. The anomaly determining accuracy of these new control charts is about tea times higher than that of Shewhart’s control charts.These new control charts will find widespread use in both commercial and industrial areas.