An Economic Alternative to the c Chart

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Black, Ryan William
Pure sciences; Applied sciences; c chart; Economic quality control; Poisson; Quality control; Regression; Statistical quality control; Applied Statistics; Statistical Models
thesis / dissertation description
Because the probability of Type I error is not evenly distributed beyond upper and lower three-sigma limits the c chart is theoretically inappropriate for a monitor of Poisson distributed phenomena. Furthermore, the normal approximation to the Poisson is of little use when c is small. These practical and theoretical concerns should motivate the computation of true error rates associated with individuals control assuming the Poisson distribution. An economic alternative to the c chart is described as a statistical model of upward shift from c0 to c1 and the two charts are compared in theory. For a range of c chart costs the savings associated with economic design increase linearly.