How the Extreme Range Method Measures Chinese City Green Competitiveness

To objectively and scientifically assess Chinese cities' green competitiveness, the research team adopted the “extreme‑range standardization method” (hereafter referred to as the “range method”) for the 2016 City Green Competitiveness Index.

The calculation process standardizes 44 third‑level indicators, distinguishing between positive (higher values benefit competitiveness) and negative (higher values hinder competitiveness) indicators.

For a positive indicator, the standardized value is computed as:

For a negative indicator, the standardized value is computed as: where z is the standardized value, x is the original indicator value, min and max are the sample minimum and maximum respectively. The range method transforms raw data linearly to the 0‑1 interval, reducing value disparity, tightening distribution, and avoiding negative results. Moreover, it enables reliable vertical (time‑series) comparisons, ensuring methodological consistency across successive reports and preventing result bias from methodological changes.

After standardization, each indicator is weighted according to predetermined weights and aggregated to obtain scores for higher‑level indicators. Summing the weighted scores of the four primary indicators yields the final city green competitiveness index.