Shewhart charts are the most commonly utilised control for process monitoring in industries with assumption that underlying distribution of quality characteristic is normal. However, this may not always hold true practice. In paper, weighted-variance mean developed and their population standard deviation estimated using three subgroup scale estimators, namely deviation, median absolute trimmed ...

Control charts are themost extensively used technique to detect the presence of special cause variations in processes. They can be classified intomemory andmemoryless control charts. Cumulative sum and exponentially weightedmoving average control charts are memory-type control charts as their control structures are developed in such a way that the past information is not ignored as it is done i...

Shewhart X¯ control charts commonly used for monitoring the mean of a process may be inaccurate or perform poorly when subgroup size is small distribution variable skewed. Truncated saddlepoint distributions can increase accuracy estimated limits by including higher order moments/cumulants in their approximation, yet this not exist lower tail, and thus limit exist. We introduce novel modificati...

Western Electric (1956) and Nelson (1984) proposed rule sets to detect visually obvious process upsets on a control chart. Performance evaluation of these rules require simulating situations that correspond their intended detection purposes such as linear drift, cycling, seesaw sustained mean shifts. These non-random patterns become in the presence reduced variation. Contrary previous assessmen...

Shewhart charts, also known as control charts, are important Statistical Process Control (SPC) techniques used for prompt detection of failures in a manufacturing process and minimization of production costs. Techniques have been used to find the chart’s parameters that best comply with economic and statistical requirements. In this paper a method that integrates a Greedy and a Tabu-Search (TS)...

Generally, the traditional Shewhart p chart has been developed by for charting the binomial data. This chart has been developed using the normal approximation with condition as low defect level and the small to moderate sample size. In real applications, however, are away from these assumptions due to skewness in the exact distribution. In this paper, a modified Exponentially Weighted Moving Av...

Analysis of Means (ANOM) is a rational extension of the Shewhart control chart for comparing products from different design configurations in off-line quality improvement. ANOM is a powerful graphic-tool for engineers to present and interpret experimental results. We apply the ANOM idea to the analysis of lifetime data resulting from experiments planned for enhancing product reliability. The ma...

Classical control charts are very sensitive to deviations from normality. In this respect, nonparametric charts form an attractive alternative. However, these often require considerably more Phase I observations than are available in practice. This latter problem can be solved by introducing grouping during Phase II. Then each group minimum is compared to a suitable upper limit (in the twosided...