Fuzzy analytic hierarchy process-integrated statistical process control: An application of demerit chart at furniture manufacturing company

Statistical process control techniques, especially control charts, have been popular tools for tracking and analysing the quality improvement process. Control charts make measurements in respect to the central line and the upper and lower control limits of a process and allow corrective action to be taken. It may be not adequate when the quality characteristics include properties requiring the usage of linguistic variables (e.g., very poor, poor, average, good, and very good) rather than identifying them just conforming or nonconforming. The demerit chart is a control chart for attributes that allows the arrangement of the relative exact weight (real number), consistent with the various levels of defects. In this paper, in order to hire linguistic weights, a demerit chart was integrated with fuzzy analytical hierarchy process, mainly through the determination of weights in accordance with the degrees of defects, after which the central line and upper and lower limits were calculated.