GRAFIK PENGENDALI ROBUST BIVARIAT DENGAN ESTIMATOR MEDMAD SEBAGAI ALTERNATIF GRAFIK PENGENDALI HOTELLING’S T2; A ROBUST BIVARIATE CONTROL CHART USING MEDMAD ESTIMATOR AS ALTERNATIVE TO THE HOTELLING’S T2 CONTROL CHART

Rahmahdewi, Sita, Subanar

2016 | Skripsi | FMIPA

Control charts are the most popular tools to monitor industrial process. Many industrial processes are monitored with several quality characteristics at the same time because there are correlated variables. However Shewhart control chart can’t be used and can lead improper informations. Hotelling’s T2 control chart is used to monitor multivariate process. It used mean as estimator for location parameter. Mean has null breakdown point which sensitive for detecting outlier and not robust. The proposed control chart use median and median absolute deviation (MAD) for location and scale parameters. Both of the estimators have breakdown points 12? and robust. For study case, consider a production process of raw meal in PT Holcim Indonesia. The data consists of two quality characteristics which are silica modulus and iron modulus. Then the process are monitored using the proposed control chart and compared with Hotelling’s T2 control chart and robust bivariate control chart using Minimum Covariance Determinant (MCD) estimator.

Kata Kunci : bivariate control chart, robust, MEDMAD, breakdown point