The 2018 Best Countries rankings, formed in partnership with global marketing communications company Y&R's brand strategy firm, BAV Group, and the Wharton School of the University of Pennsylvania, are based on a study that surveyed more than 21,000 global citizens from four regions to asses perceptions of 80 countries on 75 different metrics. The Quality of Life subranking is based on an equally weighted average of scores from nine country attributes that relate to quality of life in a country: affordable, a good job market, economically stable, family friendly, income equality, politically stable, safe, well-developed public education system and well-developed public health system. The Quality of Life subranking score had a 17 percent weight in the overall Best Countries ranking.
https://www.usnews.com/news/best-countries/quality-of-life-rankings