PHASE Ⅰ CONTROL CHARTS FOR TIMES BETWEEN EVENTS

摘要

A count of the number of defects is often used to monitor the quality of a production process. When defects rarely occur in a process, it is often desirable to monitor the time between the occurrence of each defect rather than a count of the number of defects. An exponential distribution often provides a useful model of the time between defects. Phase Ⅰ control charts for exponentially distributed processes are discussed. Methods for computing the control limits are given and the overall Type ? error rates of these charts are evaluated.