To be quite cynical, I think this is a textbook sociological study. You take a loaded word like happiness, twist the definition into something that fits both A

To be quite cynical, I think this is a textbook sociological study. You take a loaded word like happiness, twist the definition into something that fits both A.) what you can easily measure on a survey and B.) gives you results that fits your own preconceived idea of who should be happy (the Nordics) . Then you publish your study claiming you've found the keys to happiness, or if you're too modest to do that then the lay media makes such a claim.