Technology OPPO, OnePlus, Huawei rank high in smartphones survey Updated : August 28, 2019 06:51 AM IST The top-selling brands like Xiaomi, Samsung and Vivo fell behind in the overall NPS score, according to the survey conducted by Numr Research, a market research company in India. The findings in this survey are based on the responses of over 500 respondents who were between 25 and 60 years of age at the time of the survey. Net Promoter Score, popularly known as the NPS, is a metric for calculating customer satisfaction and loyalty. Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.