استقرار و طراحي آماري نمودار كنترل T2 هتلينگ با نرخ نمونه گيري متغير با استفاده از الگوريتم ژنتيك

Statistical Design of The Hotellingʹs T2 Control Chart with Variable Ratio Sampling Scheme

The familiar multivariate process monitoring and control procedure is the Hotellingʹs T2 control chart, a direct analog of the univariate shewhart x chart. But, its efficiency for detecting small to moderate shifts in the process mean is poor. To improve the power of chart, this paper studies the statistical design of the T2 chart with variable ratio sampling scheme. It is assumed that the length of time the process remains in control has exponential distribution. The chart is modeled using Markov chains and is optimized using genetic algorithm optimization method. The results show that the T2 chart with variable ratio sampling scheme is quicker than the classical one in detecting almost all shifts in the process mean.