4.5. Determine gradations (sectors

4.5. Determine gradations (sectors of scale) of sustainability

Graded levels of sustainability are necessary for convenience of communication. For instance, a two sector (‘ sustainable ’ and‘ unsustainable ’) mode is currently the most widely used. On the other hand, IUCN (1995) and Prescott-Allen (1997) have proposed a five-sector scale (1–20, bad; 21–40, poor; 41–60, medium; 61–80, OK; and 81–100, good) in the Barometer of Sustainability. Moreover, as the measurement process becomes more sophisticated, more detailed sectors may be required. Four possible models of sustainability gradation are suggested below . It is assumed that the ‘excellent’ condition of the state of health in system quality is likely to be more ‘sustainable’, while the ‘bad’ condition is likely to be defined as more ‘unsustainable’.