This might mitigate the effects, although perhaps in unpredictable ways, since the weighting algorithms that different pollsters use are as much an art form as a science.
Howard Wolfson, the executive director of the Democratic Congressional Campaign Committee, said he had seen instances this year where two polls by different pollsters in the same district had produced findings so different that it was as if they had come from different states.
The point is this -- the results being produced by different pollsters are coming to very different conclusions on the age distribution of the likely electorate.
"Anticipating what the turnout is going to be in such a one-off election is extremely difficult, and that led to different assumptions by different pollsters," Podhorzer explained in a conference call with reporters on Wednesday.
National adult samples provide the most accurate comparisons across polling organizations, while polls of likely are more problematic, as likely voters are defined in very different ways by different pollsters, introducing inconsistency.
In many swing states, successive polls carried out by the same pollsters, using the same sampling procedure, have showed Obama gaining ground.
He leaves out that Pew Research's Obama approval percentages also tend to be slightly lower than those of other pollsters using similar methods (although not by as much).
(Some pollsters using automated calls, though, attempt to supplement their samples by, for instance, using online panels).
Turnout is key, and pollsters use different models to project the likely electorate.
Pollsters use different questions and methodologies.
