Journal of Simulation, 14(1):21–40, 2020. Recipient of the KD Tocher Medal, 2019-2020, The Operational Research Society.Paper doi abstract bibtex
Consider the multi-objective ranking and selection (MORS) problem in which we select the Pareto-optimal set from a finite set of systems evaluated on three or more stochastic objectives. Solving this problem is difficult because we must determine how to allocate a simulation budget among the systems to minimize the probability that any systems are misclassified. Toward determining such a simulation budget allocation, we characterize the exact asymptotically optimal sample allocation that maximizes the misclassification-probability decay rate, and we provide an implementable allocation called MO-SCORE. The MO-SCORE allocation has three salient features: (a) it simultaneously controls the probabilities of misclassification by exclusion and inclusion; (b) it uses a fast dimension-sweep algorithm to identify phantom Pareto systems crucial for computational efficiency; and (c) it models dependence between the objectives. The MO-SCORE allocation is fast and accurate for problems with three objectives or a small number of systems. For problems with four or more objectives and a large number of systems, where modeling dependence has diminishing returns relative to computational speed, we propose independent MO-SCORE (iMO-SCORE). Our numerical experience is extensive and promising: MO-SCORE and iMO-SCORE successfully solve MORS problems involving several thousand systems in three and four objectives.