Application of Quality Control Charts in the Evaluation of the Acidity Index of Extra Virgin Olive Oil
Abstract
Statistical quality control is a system that employs statistical techniques to control quality by carrying out inspection, testing and analysis to conclude whether the product quality is in accordance with established quality standards. In this article we present the application of control charts of quality in the evaluation of the acidity index of extra virgin olive oil. In this study we present and show the application of some Quality Control Charts in a sample of 58 individual observations of the acidity index (in%) of extra virgin olive oil of a certain brand. The charts used are Cumulative Sum Chart (CUSUM) and Exponentially Damped Moving Average Chart (EWMA), in addition to presenting the application of these two charts, we performed a comparative analysis with charts I (Graph X) and range (MR). application of the charts, some assumptions of their application were verified, such as data normality through the Ryan-Joiner test (Similar to Shapiro-Wilk), serial autocorrelation and the existence or not of outliers through the boxplot. With a significance of 1% and 5 % we verified that the oil acidity index data had approximately a normal distribution, there was no presence of outliers. As for the results of the charts, we observed points that were outside the control limits on chart I, as corrective actions we removed the points that were outside the control limits on the MR chart, where we found that the process seemed to be under statistical control and to be capable, but on the CUSUM and EWMA charts we still check points outside the control limits.
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References
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