Furlong, S.R. (2005), "Exploring Interest Group Participation in Executive Policymaking," in The Interest-Group Connection: Electioneering, Lobbying, and Policymaking in Washington, eds. Herrnson, P. et al., Washington, CQ Press.
The most common way for interest groups to participate in the executive branch policymaking process is through participation in notice and comment rulemaking. Furlong notes that there are many rulemaking activities that have significantly greater business organization participation than citizen advocacy or public interest group participation. Furlong reviewed the percentage of comments from each type of interest group during the first six months of 1996. Ultimately, membership organizations tend to prefer lobbying the legislative branch, and economic interest groups prefer lobbying in the administrative process.
My take: Furlong needs to explain how he categorized interest groups for his review of notice-and-comment rulemaking; otherwise, his analysis isn't reliable.