Spatial Shang

It is a spatial version of the Shang method, where “spatial” means that it is suitable for problems of spatial location. The Spatial Shang is applicable when the research problem involves issues related to the choice of the best geographical location. The main steps of the Spatial Shang are the following: 1) Selection of the panel of participants (say). 2) Construction of the first questionnaire on a digital map, in which the decision problem is formalized following a “spatial logic”, such as “the most appropriate location for …”, “the most appropriate location where …” or “the place where most likely the future event X will occur”. 3) The experts are invited to place four points on the map, among which two are the extreme positions along latitude and two are the extreme positions along longitude. 4) From the first consultation the results are rectangles on the map, which allows allows dividing the rectangle into four sub-rectangles, each having a quarter of the area of the rectangle. 5) Second round of consultation. The research question is proposed to the panel in the form of the same map with the addition of the four sub-rectangles. The experts are invited to choose one of the sub-rectangles to indicate where the best area is for the spatial problem under study. 6) The sub-rectangle with the majority of preferences becomes the new rectangle of consensus which, once calculated its center of gravity, will be divided in four sub-rectangles. Now, each sub-rectangle has a sixteenth of the area of the initial rectangle (in case two sub-rectangles receive the same number of preferences, the Spatial Shang considers a solution by calculating the distance between the points). 7) Iterations. Further rounds are performed, selecting new sub-rectangles, until a sufficiently small portion of territory is delimited, that is a small rectangle that represents the solution to the spatial problem.