Recent studies have shown that the 2 T control chart with variable sampling intervals (VSI) and/or variable sample sizes (VSS) detects process shifts faster than the traditional 2 T chart. This article extends these studies for processes that are monitored with VSI and VSS using double warning lines ( DWL T − 2 ). It is assumed that the length of time the process remains in control has exponent...

Quality control is one of the most used statistical applications in industry. The control of attribute quality characteristics is a subject of study due to the need of improving the efficiency of the charts. The present paper deals with the improvement of the classical u chart, using the Daudin strategy, based in a double sampling scheme and a variable sample size. The DS-u chart is proposed. T...

One of the objectives of the research done in statistical process control is to obtain control charts that show few false alarms but, at the same time, are able to detect quickly the shifts in the distribution of the quality variables employed to monitor a productive process. In this paper the synthetic-T control chart is developed, which consists of the simultaneous use of a CRL chart and a Ho...

In most real-world applications, such as production and manufacturing processes, the underlying process distribution does not always follow a normal distribution. cases, statistical control literature recommends use of nonparametric (or distribution-free) charts. This paper introduces new distribution-free precedence chart using repetitive sampling. The performance proposed is investigated in t...

To keep an eye on the status of high-quality processes for fraction nonconforming, synthetic double sampling (SDS) np chart is a helpful tool. The SDS hybrid between (DS) and conforming run length (CRL) chart. performance control typically judged solely using average (ARL). However, as shape (RL) distribution varies with magnitude shift in process ARL no longer provides clear interpretation cha...

Decision procedures for monitoring industrial processes can be based on application of control charts. The commonly used p-chart and np-chart are unsatisfactory for monitoring high-quality processes with a low fraction nonconforming. To overcome this difficulty, one may develop models based on the number of items inspected until r (P 1) nonconforming items are observed. The cumulative count con...