Performance Measures for a Single-Change-Point Nonstationary Control Chart Policy
Titel:
Performance Measures for a Single-Change-Point Nonstationary Control Chart Policy
Auteur:
Marcellus, Richard L.
Verschenen in:
IIE transactions
Paginering:
Jaargang 35 (2003) nr. 12 pagina's 1111-1123
Jaar:
2003-12
Inhoud:
Single-change-point policies are defined as control chart policies where the charting procedures are changed exactly once at a preselected time. A special class of these policies is studied, namely those where decisions whether or not to look for an assignable cause are always based on a single sample. For these policies, the paper presents average run lengths, the expected number of false alarms per production cycle, the expected number of samples, the expected number of sampled items, and the expected time required to detect an assignable cause. Theoretical conditions are given for the single-change-point policies to have a better performance than stationary policies. In addition, numerical exploration reveals that the largest improvements occur when assignable causes result in a relatively small shift in the mean and the expected occurrence time of the assignable cause is relatively small with a low variability. This, along with previous work by other authors, shows that extensive investigation of nonstationary policies would be worthwhile. The results may be directly extended to all charts of Shewhart type.
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