کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1134742 956077 2010 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Comparisons of the symmetric and asymmetric control limits for X¯ and R charts
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی صنعتی و تولید
پیش نمایش صفحه اول مقاله
Comparisons of the symmetric and asymmetric control limits for X¯ and R charts
چکیده انگلیسی

Though both symmetric and asymmetric control limits can be applied to X¯ and R   charts, no well-controlled comparison of the resulting performance has been conducted. Symmetric limits such as 3-sigma limits are the customary choice. However, previous researchers have proposed asymmetric control limits as a more appropriate choice than symmetric limits for skewed distributions. This paper examines the relative performance of symmetric and asymmetric limits. It compares the out-of-control average run length (ARL) for symmetric and asymmetric limits for fixed values of the in-control ARL. Two testing examples are employed: the exponential and Johnson unbounded distributions. The results of the performance comparison are mixed. For both X¯ and R   charts, the impact of the control limit choice (symmetric or asymmetric) depends on two factors: the skewness of the charting statistic (sample mean X¯ for the X¯ chart and sample range R for the R   chart) and the shift direction. When the charting statistic has a right-skewed distribution, symmetric limits perform better if the monitored process property (the mean for the X¯ chart and the standard deviation for the R chart) shifts upward, but worse when it shifts downward. When the charting statistic has a left-skewed distribution, the outcome is reversed. Although neither type of control limits dominates even for a skewed population, the asymmetric limits are more robust to the shift in the process mean or variation. The effect of the sample size is also discussed.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Computers & Industrial Engineering - Volume 59, Issue 4, November 2010, Pages 903–910
نویسندگان
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