Authors: Reza Shokrizadeh; Mohammad Dolatabadi; Yaqub Yaqubinejad
Addresses: Department of Industrial Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran ' Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran ' Department of Mathematics, Islamic Azad University, Sirjan Branch, Sirjan, Iran
Abstract: T2 control chart with variable dimension is useful when there is a set of p1 variables that are easy to monitor or whose measurement is cheap, against a set of p2 variables, p = p1 + p2, that are difficult and/or expensive to monitor. However, the information that these p2 variables provide is important to detect quickly the process quality shift. Therefore, there are cases when controlling the whole set of p variables may be difficult or expensive, but controlling sometimes p1 variables, and only when the process seems to have a problem controlling the full set of p variables, may be a cheaper option on average and very efficient. However, its not effective if the shift size is small. For obtaining good performance in detecting such shifts, we propose the application of the variable sampling interval technique to the variable dimensional T2 (VDT2) control chart, resulting in the VSIVDT2 control chart.
Keywords: Markov chain; variable sampling interval; VSI; variable dimension; average time to signal; ATS.
International Journal of Quality Engineering and Technology, 2018 Vol.7 No.1, pp.39 - 51
Received: 23 May 2017
Accepted: 24 Feb 2018
Published online: 07 Sep 2018 *