This is very close to one of the key criticisms behind Net Promoter Score when we was looking at implementing it for a client. Basically it uses an 11 point sc

This is very close to one of the key criticisms behind Net Promoter Score when we was looking at implementing it for a client. Basically it uses an 11 point scale and your net promoter score is the proportion of 0-6 (negatives) subtracted from the positives (8 or 9-10). I may have got ranges wrong but the idea is the same. This was touted as "the only number you need to improve" for business success.