The idea of variable sampling interval and warning limits (VSIWL) is proposed for X charts. Expressions for the performance measures for the charts with VSIWL are developed. The methods presented are general and can be applied to other Shewhart control charts. The performances of VSIWL X charts are compared numerically with that of VSI X charts with and without runs rules for switching between ...

This paper formulates Shewhart mean (X-bar) and range (R) control charts for diagnosis and interpretation by artificial neural networks. Neural networks are trained to discriminate between samples from probability distributions considered within control limits and those which have shifted in both location and variance. Neural networks are also trained to recognize samples and predict future poi...

The setting of the control limits to utilize on a control chart supposes the assumption of the normality. However, in many situations, this condition does not hold. There are numerous studies on the control charts when the underlying distribution is non-normal. This paper examines the effects of non-normality as measured by skewness and provides an alternative method of designing individuals co...

This working paper series is intended to facilitate discussion and encourage the exchange of ideas. Inclusion here does not preclude publication elsewhere. It is the original work of the author(s) and subject to copyright regulations. ABSTRACT We believe that conflicting decision signals resulting from examining Shewhart Mean and Variability Control Charts produce undesirable consequences. Ther...

In statistical process control, the control charts are the most powerful tools for assessing the process behaviour. The Shewhart S chart is a standard tool for determining process variability. Similar to S chart, the chart based on Median Absolute Deviation from the sample median namely MAD estimator is also considered robust for both normal and non-normal processes. As ̅ and are considered unbi...

Shewhart control charts are suitable for stable but repetitive production processes used the subsequent identification of random deviations while indicating breached quality limits. They provide information on process variability and, at same time, make it possible to obtain reliability monitored processes. The objective this paper is assess characteristics plastic mouldings needs automotive in...

Introduction The outcome of thyroid surgery is usually assessed according to two major complications: recurrent laryngeal nerve paralysis and hypoparathyroidism. The purpose of the study was to monitor the outcomes of thyroid surgery using Shewhart control charts, and then to identify possible ways to improve quality by exploring the special causes of variation in the observed complication rate...