A generally weighted moving average chart for time between events

Shewhart-type attribute charts are known to be inefficient for small changes in monitoring nonconformities. An alternative way is to use a time-weighted chart to monitor the time between events (TBE). We propose a one-sided Generally Weighted Moving Average control chart to monitor the time between events (TBE); regarded as the GWMA-TBE chart. To aid the implementation of the chart, the necessary design parameters are provided. An extensive performance analysis shows that the GWMA-TBE chart is better than the well-known EWMA and Shewhart charts at detecting very small to moderate changes. Finally, a summary and some conclusions are provided.STATOMET (Grant number: SMB2015A), University of Pretoria, South Africa.http://www.tandfonline.com/loi/lssp202018-05-09hj2018Statistic

The use of fast initial response features on the homogeneously weighted moving average chart with estimated parameters under the effect of measurement errors

Fast initial response (FIR) features are generally used to improve the sensitivity of memory-type control charts by shrinking time-varying control limits in the earlier stage of the monitoring regime. This paper incorporates FIR features to increase the sensitivity of the homogeneously weighted moving average (HWMA) monitoring schemes with and without measurement errors under constant as well as linearly increasing variance scenarios. The robustness and the performance of the HWMA monitoring schemes are investigated in terms of numerous run-length properties assuming that the underlying process parameters are known and unknown. It is found that the FIR features improves the performance of the HWMA monitoring scheme as compared to the standard no FIR feature HWMA scheme, and at the same time, it is observed that the simultaneous use of a recently proposed FIR feature and multiple measurements significantly reduces the negative effect of measurement errors. An illustrative example on the volume of milk in bottles is used to demonstrate a real-life application.https://wileyonlinelibrary.com/journal/qrehj2022Statistic

Some theoretical comments regarding the run-length properties of the synthetic and runs-rules monitoring schemes – Part 1: zero-state

Please read abstract in the article.The SARChI Chair at the University of Pretoria, the National Research Foundation (NRF) and Department of Science and Technology’s Innovation Doctoral scholarship, and the Department of Statistics’ STATOMET.hj2020Science, Mathematics and Technology EducationStatistic