Effectiveness of Interest Groups

What does control over investment mean?

I like your survey questions. I wonder if "interest groups" is too broad though? I personally think, for example, large energy (oil) firms and trade associations would have significantly more effectiveness than aboriginal groups.

Another resource I would imagine some groups have to influence government is the amount of votes they could sway, for example a union telling its members how to vote. Does this count under "Public Opinion" you think?