The index values are calculated as weighted shares of responses. Each answer of “extremely pressing problem" is multiplied by a factor of 1, “pressing problem” by 0.75, “average problem” by 0.5, “small problem” by 0.25, and “no problem at all” by 0.

The index values thus span from +100 (if all participants answer “extremely pressing problem”) to 0 (if all participants answer “no problem at all”).