OPTIMAL TARGET VALUES FOR A FILLING PROCESS WHEN INSPECTION IS BASED ON A CORRELATED VARIABLE

The problem of selecting optimal target values for the mean of the qua ntity Y of material in a container and the cutoff value on a correlate d variable X is considered for a filling process in which a container is nonconforming if its Y value is less than the lower specification l imit and inspection is based on X instead of Y. A profit model is cons tructed which involves selling price and filling, rework, inspection, and penalty costs. Assuming that X and Y are jointly normally distribu ted, a method of finding the optimal process mean and the cutoff value on X is presented. An example from the cement industry is presented.