Three-point scale: this is divided into three sectors of 33.3 points each, totaling 100. However, for the convenience of calculation, and to avoid confusion in interpretation, these ranges are reorganised: 33% vs. 34% vs. 33%. This model may be useful in explaining relatively simple information to stakeholders, as the scales are divided into relatively simple sectors among the four models:
sustainable (good): 68–100%;
intermediate (medium): 34–67%; and
unsustainable (poor): 1–33%.
Two-point scale: it is divided into two sectors of 50 points each totaling 100. This model may be useful in explaining very simple information to stakeholders, as the scales are divided into the simplest sectors among the four models:
sustainable (good): 51–100%; and
unsustainable (poor): 1–50%.
In this paper, these four gradations of sustainability levels are used in developing SAMs, and where accurate data are lacking, only a two or at most a three-point scale may be appropriate. Although more detailed gradations (e.g. 10 divisions) could be introduced, they may be unrealistic in practice.