So, in case anyone ever asks again, here it is.
There is precedent for Rasmussen erring huge in favor of Republicans
by: Chris Bowers
Mon Apr 19, 2010 at 14:43
Rasmussen Reports has become a controversial polling outfit in this election cycle, for two reasons: a massive increase in the amount of polling it produces and its newfound "house effect" in favor of Republican candidates.
First, during 2009-2010, Rasmussen Reports has produced has drastically increased its quantity of polling. For example, in addition to their daily tracking poll on President Obama's job performance and their weekly poll on the generic congressional ballot, 28% of all the polls conducted on the 2010 Senate elections, up from 18% in 2007-2008.
Second, and most importantly,
Rasmussen has become controversial because its massive amount of polling has skewed decidedly in favor of Republican candidates. Rasmussen surveys have favored Republicans by 5.5% compared to other polling firms so far in 2009-2010. In 2007-2008, Rasmussen was in line with all other surveys, showing no House effect at all.
As Nate Silver showed over the weekend, this newfound skew in favor of Republicans is not simply the result of Rasmussen surveying likely voters while other polling firms are looking at registered voters or all adults. Comparing apples to apples, Rasmussen's likely voter generic congressional ballot polls favor Republicans by 6% compared other likely voter generic congressional ballots. Further, Rasmussen's numbers for partisan identification among all adults also favor Republicans by about 6% compared to other polls that measure partisan identification among all adults.
To reiterate: Rasmussen's likely voter polls are skewing 6% in favor of Republicans compared to other likely voter polls, and Rasmussen's polls of all adults are skewing 6% in favor of Republicans compared to other polls of all adults. So, this has nothing to do with an enthusiasm gap or a likely voter screen. Rasmussen is simply flooding the zone with polls that skew towards Republicans by an average of 6%.more...
http://www.openleft.com/diary/18340/there-is-precedent-for-rasmussen-erring-huge-in-favor-of-republicans