Multivariate Control Charts; Fuzzy Set; Membership Function; Probability
A good product must satisfy the standard of corresponding quality characteristic. A product is categorized as defect when its quality characteristic out of its specification limit. The measurement of quality characteristic may produce errors because it measures quality around its actual value instead of the actual value itself. This measurement error can produce an ambiguity. Some approaches have been developed to tackle this ambiguity problem. This research employed T2 Hotelling Fuzzy and W2 control chart with probability approach to deal with this issue. The proposed methods were applied to monitor the wheat flour production process. Three variables, multivariate processes, were used to identify the product quality such as moisture, gluten, and ash. The membership function used fuzzy approach is a combination of trapezoidal and linear curves. This research concluded that W2 control chart with probability approach performed better than T2 Hotelling Fuzzy control chart.