::Agreed, I have been giving this a lot of thought over the past few days and now see that interest group is much wider than advocacy group and that advocacy group is a type of interest groups but that interest group is also used as a euphemism for advocacy group and lobbying group but that it is more helpful to keep the concepts clearer. It may be appropriate at some point to move Special Interest group to fill the 'interest group' disambiguation page with a clear link to advocacy and lobbying in the lead. Personally I think that is probably the best long term position, but lets see if this move is successful first. I may do some work on the special interest group article now to make the relationship clearer.