“Surveys like this usually have the following type of scoring:
minus 5 points for civilian access to guns
plus 5 points for easy access to abortion
plus 5 point for state-run medicine
plus 5 points for availability of assisted suicide “
What is your source on that?
Experience. I have seen surveys in the past with loaded questions.
The study methodology will be biased based on the survey designer's opinions about the factors cause happiness. My impression is that these studies are done by Leftist groups with grants. Sometimes there is an agenda, and sometimes there is bias.
According to the documentation for this particular survey, the following factors were included.