Fordata normalization, each indicatorwas divided by its standard
deviation so that at the end, all the indicators received a standard
deviation equal to 1. For the determination of proportional
coefficient, we used the linear scoring method; here, indicators
are ranked in ascending ordescending orderdepending onwhether a
higher valuewas considered“good”or “bad” in terms of soil function.
For “more is better” indicators, each observation was divided by the
highest observed value such that it received a score of 1 and the
remainder less than 1. For “less is better” indicators, the lowest
observed (in the numerator) was divided by each observation
(in denominator) such that it received a score of 1 and the remainder
less than 1. The indicator scores vary between 0 and 1. A score of 1
was given when an indicator value represented high function.
Combination of transformed indicators by their proportional
coefficients gave a product (WiXi) and the soil quality index (SQI)
parameter was computed by summing scores for each variable
according to the method described by Andrews et al. (2002a,b).