Adaptive control charts deliver significantly better performances than that of static control charts. However, the frequent switches between sampling interval lengths and/or between sample sizes can be a complicating factor in the administration of these charts. This factor is totally absent...

A modified median chart with estimated control limits is proposed for monitoring the mean value of a normal process. The estimates for the nominal process parameters used to set up the control limits in Phase I are the average of the sample medians and the average of the sample ranges of m...

Procedures for continuously monitoring binary attribute data processes are of utmost relevance for fields like electrical engineering, chemical production, software quality engineering, healthcare monitoring, and many more. In this article, new approaches are proposed, where kth order runs in a...

Purpose – The purpose of this paper is to propose a methodology that may assist quality professionals in assessing process variation with a combination of tools based on simple robust statistics. The technique targets alternative way of screening and detection of common and special causes in...

The np chart and the binomial cumulative sum (CUSUM) chart are attribute charts that monitor the fraction non-conforming p. While the np chart is effective for detecting large process shifts in p, the CUSUM chart is more powerful for detecting small and moderate p shifts. This article presents...

Control charts have been widely recognised as important tools in system monitoring of abnormal behaviour and quality improvement. Traditional control charts have a major assumption that successive observations are uncorrelated and normally distributed. When this assumption is violated, the...

Shewhart X charts are often used in industries to detect the larger shifts in the process mean. One of the assumptions while implementing these charts is that the observations from the process output are Independent and Identically Distributed (IID), but in actual practice, the observations are...