How liberal are Barack Obama and Hillary Clinton, and how conservative is John McCain? Believe it or not, there is an objective mathematical method, called Optimal Classification (OC), that lets you calculate such things if you have enough data to work with. UCSD political scientist Keith Poole, who developed OC, just finished ranking the US Senate based on the roll call votes from the first half of the 110th Congress,and the results are quite interesting.
So, where do the presidential candidates stand? Turns out that Obama is the about the 10th most liberal Senator (Feingold is the most liberal), Clinton is the 20th, and McCain is the 94th.
This isn't just another opinion. As odd as it may seem, it's actually hard science. OC is purely mathematical; there are no value judgments or subjective decisions involved. It's not often that you can separate the underlying truth from all the BS in politics, but this is one exceptions.
When I get a chance I'll graph how the presidential candidates' rankings have changed over time. For a self-proclaimed straight talker, McCain has had some particularly intriguing ideological swings during critical periods of his long political career.
OC is a unique tool that deserves to be more far widely understood and applied, and I'll be writing more about it in the future.