[nils-m-holm]

The study followed the people who took part in it for nine months and did a follow-up survey six months after the end of the experiment. However, the follow-up results were only obtained when the report was already finished.

Here is the complete report (in Swedish): http://ltblekinge.se/globalassets/forskning-och-utveckling/b...

They mention a smiliar study from the US, but here money was only one out of multiple factors:

https://www.researchgate.net/publication/229888823_Supported...