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The purpose of this research is to enhance performance for detecting a change in process mean by combining modified exponentially weighted moving average and sign control charts. This is a nonparametric control chart which effective alternatives to the parametric control chart, so called MEWMA-Sign. The nonparametric control chart can serve when process observations are deviated from normal distribution assumption. Generally, the performance of control charts is widely measured by average run length (ARL) divided into two cases; in control ARL (ARL0) and out of control ARL (ARL1). In this paper, the performance comparison is investigated when processes are non-normal distributions. The performance of the MEWMA-Sign is compared EWMA-Sign control chart by considering a minimum value of ARL1. The numerical results found that the MEWMA-Sign performs better than EWMA-Sign in order to detect a very small shift of mean process. Additionally, the real application of the MEWMA-Sign and EWMA-Sign are presented.
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