John gives some reasons why viewers of the political scene might think that congressional Republicans are more disciplined than their Democratic counterparts, even if this isn’t really so.

I’d like to give one more big reason based on recent history. When Barack Obama became president, congressional Republicans implemented a solid No strategy and were successful at stopping much of the Democrats’ agenda. With only 40% of each of the houses of Congress, the Republicans had few tools except party discipline. To me, it is this impressive achievement that earns congressional Republicans their reputation.

Everything John wrote is fine but I think he’s missing the elephant in the room (so to speak).

Andrew Gelman is a professor of statistics and political science and director of the Applied Statistics Center at Columbia University. He has received the Outstanding Statistical Application award from the American Statistical Association, the award for best article published in the American Political Science Review, and the Council of Presidents of Statistical Societies award for outstanding contributions by a person under the age of 40.