Through standardization the original factor scores (each expressed in its own unit of measurement) are converted into dimensionless scores in the 0 (worst situation) or 1 (best situation) range.
In the present study standardization was performed by using both linear functions and sigmoidal monotonically decreasing functions, as illustrated in Fig. 6. Linear standardization functions assume that a linear relationship exists between the impact scores and the perceived significance of the impacts. This method offers the advantage of keeping the ratio between the original impact scores and the standardized ones. The sigmoidal function is instead based on the cosine function and evaluates the fuzzy set membership values (possibilities) of data cells (Eastman, 2006).