Closing assessment

The three methods differ in their underlying scale: they range from ordinal (weighting by ranking), to interval (weighting by rating), to ratio scale (pairwise comparison). While the first two stand without theoretical basis, the last method can be statistically secured. Which of the three approaches used depends on a number of questions: how accurate does the analysis need to be? How vast is the experts’ expertise and experience with weighted overlay? How difficult is the method’s integration into a GIS? The risk in using weights in a spatial MCE is the inexperienced, careless, or even erroneous determination of weights. Wrong weights lead to wrong results of suitability analysis and thus to wrong decisions. This risk exists in all three methods since ultimately, the weighting is the responsibility of experts. Therefore, each suitability map should inform in detail how it was created and what its underlying assumptions are.