by davidshor, Thu Feb 25, 2010 at 01:03:19 PM EST
It's already well established that Rasmussen polls are consistently to the right of other polls, and this is often explained in terms of legitimate differences in methodological minutiae. However, looking at the a large database of Rasmussen polls, it seems that their pro-republican bias, or House Effect, is not monolithic. There seems to be evidence that Rasmussen's house effect is much larger when Republicans are behind, and that it appears and disappears quickly at different points in the election cycle.
See graphs and more below the fold or at StochasticDemocracy.com