Input data used in Multi-Attribute Decision Making (MADM) problems are often perceived to be imprecise by decision-makers because they are based on expert assessments. As a result, an important step in many applications of MADM is to perform a sensitivity analysis on the input data to help decision-makers understand how in which regions of the input data space they can be most confident in the recommended decisions and where improved input information is most needed. This paper describes sensitivity analysis procedures which will help decision-makers examine the robustness of the optimal solution to changes in input parameters in system selection decisions, where the system is made up of components (drilling technologies) that can be combined in many different ways. This paper presents two different sensitivity analysis methodologies. One is a sensitivity analysis for weighting factors of each attribute, and the other is a sensitivity analysis for uncertainty of overall attribute inputs. An application case study of the proposed approach is described to select optimal onshore Environmentally Friendly Drilling (EFD) systems at Green Lake near McFaddin, TX. © 2011 Wiley Periodicals, Inc.