Professor Bruno Frey has studied happiness in Switzerland, comparing one region (or Canton) with another. He concludes that "The better the opportunities for direct influence on political decisions per referendum are, the more satisfied the people will be." More here.
In his article "Happiness Prospers in Democracy", based on a survey of 6000 people in Switzerland, he writes
- "the more developed the institutions of direct democracy, the happier the individuals are;
- people derive procedural utility from the possibility of participating in the direct democratic process over and above a more favourable political outcome"
Bruno Frey is Professor of Economics at Zurich University. Here's his web site, which includes many articles.