For instance, what are the differences between the concepts like depression, mental health, well-being, happiness, and life satisfaction? Are they synonymous? It is clear that the literature of subjective well-being in economics uses happiness or life satisfaction or sometimes mental health measures such as GHQ-12 as a sort of proxy for the utility. In the terminology of Kahneman, these are all proxies for the experienced utility. What is “depression” in this context?