There is a similar study that finds Latin American countries to be among the happiest. Discussed here:
http://www.livescience.com/50209-happiest-countries-latin-am...
There is little of the social conflict, poverty, health problems etc which plague many other countries.
That is what these things measure. Latin American countries would typically get pulled down because there is a signifiant portion of people who don't have very nice lives. This is what I've heard from foreigners living in northern Europe. They notice that there are very few people you observe who look genuinely dissatisfied with their life.
Please don't. That was the creation of one author that was a bit of a grump to put it mildly.
Also, he formulated that in the 1930s.
I think the problem arises from most resumes being BS, so if your resume doesn't claim you have 20 years experience in a 5-year-old technology, etc., recruiters probably think you're a complete loser. Well, that and the fact that most recruiters don't seem to have the reading comprehension of a dead badger...
Which has an implicit assumption that happiness = living your "best possible life".
There are definitely people in Africa, Latin America, etc, who recognize they may have better prospects elsewhere, but if they're content with where they are… isn't that happiness too?
It's not pessimism vs. optimism, it's that numeric ratings have no intrinsic, universal mapping to feelings, and cultures tend to map them differently.
Such rigor!