Abstract
The double sampling (DS) Xbar chart is effective in detecting small to moderate process mean shifts and reducing the sample size. The average run length (ARL) is an intuitively appealing and widely used optimization criterion in the design
of a control chart. Nevertheless, the skewness of the run length distribution changes with the size of the process mean shift; thus, ARL is not necessarily a good representative of the run length distribution. In such a case, the median run length (MRL) provides a more reliable interpretation, for the in-control and
out-of-control performances of a control chart. In this paper, an optimal design of the DS Xbar chart based on MRL is proposed. New optimal parameters are provided for selected in-control median run lengths, MRL0 ∈ {250, 500} and in-control average sample sizes, ASS0 ∈ {3, 5, 7, 9}. These optimal parameters facilitate the implementation of the DS Xbar chart in practice.
of a control chart. Nevertheless, the skewness of the run length distribution changes with the size of the process mean shift; thus, ARL is not necessarily a good representative of the run length distribution. In such a case, the median run length (MRL) provides a more reliable interpretation, for the in-control and
out-of-control performances of a control chart. In this paper, an optimal design of the DS Xbar chart based on MRL is proposed. New optimal parameters are provided for selected in-control median run lengths, MRL0 ∈ {250, 500} and in-control average sample sizes, ASS0 ∈ {3, 5, 7, 9}. These optimal parameters facilitate the implementation of the DS Xbar chart in practice.
| Original language | English |
|---|---|
| Pages (from-to) | 303-306 |
| Journal | International Journal of Chemical Engineering and Applications |
| Volume | 3 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - Oct 2012 |