There are two key challenges associated with subjective measures of well being, according to the OECD.3
First, what drives people’s life satisfaction may be affected by personal circumstances to which individuals adapt, even if that is not objectively good. Similarly, there may be a disconnect between subjective measures of well-being and the more objective measures. For example, the indicator self-reported health status in the Health category of this website reveals that the Japanese have the lowest self-reported health status and yet have the longest life expectancy, the lowest infant mortality rate, and the lowest rates of mortality due to circulatory diseases, diabetes, and mental disorders.
Second, it is difficult to ensure that individuals in different countries understand the question in the same way and are not affected by external factors that vary by country.
Despite these challenges, the OECD reports that “a large body of recent research has shown that these shortcomings have a limited effect on subjective measures of well-being and that it is indeed possible to make valid comparisons between different groups of people. After having long been relegated to academic research, these measures are today increasingly accepted more widely.”4