Unless it's been superceded in the last decade, the best study I know of on
the causes of happiness (or at least what factors happiness correlates
with) is Michael Argyll's The Psychology of Happiness. I bought this in
England in the '80s, so it may not be available in the U.S.
Max More, Ph.D.
<firstname.lastname@example.org> or <email@example.com>
Consulting services on the impact of advanced technologies President, Extropy Institute: