How is the SRS (Symanto Recommendation Score) being calculated?

The SRS (Symanto Recommendation Score) can be found in the 'Brand Recommendation'.
It allows you to compare the selected brands or products by their overall score calculated from the detractors and promoters. The higher the score, the better. 

This is how it is calculated:

SRS = % of promoter - % of detractor

For Streaming Service 'Netflix' the valule of Promoters is 18%, Detractors 56%; following the calculation for the SRS: 18% - 56% = -39%
The Symanto Recommendation Score is -39% as shown.