This paper treats of the historical origin of the contemporary model K=2 I M-i /T and Cpk=(1-K)Cp in the quality control and the essence of the mistakes in it. Early formula of the calculation of the engineering capability percentage under the condition of the deviation: K= M-j. I 1 and Cpk=Cp-K/3, does not agree with the condition of normalization. It should be negated, because their mathematical basis is wrong. Based on the condition of normalization, the writer proposes to use K= M-pc I /(2a) and Cpk=Cp-K/3 instead of the early formula. The contemporary model is equivalent to the early form...
