Abstract: In some production systems, upward and downward shifts of processes may cause different losses. To meet the need of quality control in these situations,this paper proposed two X〖DD(-*3〗〖KG*3〗—〖DD)〗 charts with asymmetric sample sizes. A Markov chain method was used to obtain their statistical properties. Numerical results indicate, for the shifts of less than 1.5 process standard deriation from the mean, that using asymmetric sample sizes is more efficient in detecting the shifts in one direction, while without missing the shifts in the other direction. Using the warning limit may speed up in detecting the shifts in one direction.

Key words: asymmetric sample size, Markov chain, asymmetric loss, control chart, asymmetric sample size, Markov chain, asymmetric loss