Rasmussen Reports accounts for 38 of the 141 recent likely-voter polls in my dataset from Pollster or fully 27% of all the observations. Earlier I have shown that Rasmussen has a pro-Romney “house effect” of over two percent. Given the combination of Rasmussen’s dominance and its pro-Republican bias, we might wonder what the polling consensus would be if there were no Rasmussen Reports. Here is the graph from my most recent post after excluding Rasmussen’s polling from the sample.
Without Rasmussen, we do not see evidence that the campaign has stagnated. We do find that the other pollsters recorded a somewhat larger drop for President Obama after the first debate putting him a point behind Governor Romney. However, a model that excludes Rasmussen shows no evidence of stagnation but keeps the President on his slow upward trend with a slim margin of 0.6% in the polls on Election Day. Here is the graph from the earlier post with Rasmussen included for comparison.
Full regression results are here.