When it comes to ads clicking, the general consensus I find among site owners who got dugg before was Digg users are lousy ad clickers.
Yup, I get a lot of traffic from stumbleupon but hardly any clicks. I guess they're just curious rather than looking for something.
Digg user seldom click on the ads. My website showing that the CTR from digg is less than 1% but the CTR from search engine is about 5%
Digg only temprorarily increases your traffic count and really they are just intrested in the full news so they never click on the ads. They are veteran users and they think clicking on ads is an insult to their intelegence.
i dont now exactly about the research, but from my knowledge, they re like brothers. google like digg verymuch in serp