Nate Silver has been trying to show the effect of healthcare industry lobbying on the US health care reform debate. He believes that the lobbyists’ contribution to reelection campaigns have had an effect. Brendan Nyhan disagrees, saying:
What’s so frustrating about Silver’s post, which was (disappointingly) praised by Paul Krugman on his New York Times blog, is that there is an extensive literature on this subject by political scientists and economists. Over the last 30+ years, these studies* have typically found minimal effects of campaign contributions on roll call votes in Congress even when scholars use more sophisticated techniques to address the causal inference problems described above (which are widely understood at this point). Given these prior findings and the inherent problems with Silver’s analytical approach, we should be extremely cautious about putting any weight on his conclusions.