This paper applies the methodology developed previously to quantify the contribution of process data to performance measures. It describes a refinery case study in which measurements are ranked according to the cost-effectiveness of their contribution to improving refinery performance measures. This provides a means. of evaluating the cost effectiveness of data collection, data analysis and estimation procedures on a particular refinery unit. The work is of direct benefit to the refinery as it provides an aid for making business decisions on the procedures involved in the determination of a : plant＇s performance. An example of such a decision would be investment in instrumentation since measurements make : an important contribution to the estimation of performance parameters.