Exponentially Weighted Moving Average Control Charts for Monitoring Ambient Ozone Levels in Muscat
American Journal of Theoretical and Applied Statistics
Volume 4, Issue 4, July 2015, Pages: 254-257
Received: May 20, 2015; Accepted: May 26, 2015; Published: Jun. 2, 2015
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Author
Muhammad Idrees Ahmad, Department of Mathematics and Statistics, College of Science Sultan Qaboos University, Muscat, Oman
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Abstract
Exponentially Weighted Moving Average (EWMA) control charts are proposed to monitor ambient ozone (O3) levels in the city center and industrial areas of Muscat. Weekly averages of 8-hourly concentrations of ozone over a period of one year were used. The EWMA charts showed significant shift in the mean ozone levels at both the sites. However, both the ozone series were found to have significant autocorrelation. Therefore Box-Jenkins autoregressive integrated moving average (ARIMA) models were fitted at the first stage and then residuals were taken to apply EWMA which revealed that the ozone levels in both areas are within natural tolerance limits as well as within the international standard limit.
Keywords
ARIMA, EWMA, Quality Control Charts
To cite this article
Muhammad Idrees Ahmad, Exponentially Weighted Moving Average Control Charts for Monitoring Ambient Ozone Levels in Muscat, American Journal of Theoretical and Applied Statistics. Vol. 4, No. 4, 2015, pp. 254-257. doi: 10.11648/j.ajtas.20150404.14
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