Studies of the effects of interest groups on congressional roll-call voting typically view party and ideology as competing factors and rely on a factoral model of interests or a sectoral model including only interest groups with a direct stake in the vote. We depart from that strategy in several...

Gary King, Robert O. Keohane, and Sydney Verba's <italic>Designing Social Inquiry</italic> exploits the metaphor of researcher-as-statistician to develop guidelines for conducting social scientific research that are allegedly applicable to all empirical investigations. Their approach has sharp and often...