Two major pollsters have announced changes to their methods as we get nearer to election day. Both of these should bring shifts in the polls which may strike us as sudden or dramatic, so be aware.
Public Policy Polling has made the shift from Registered Voters to Likely Voters in its polling, according to the pollster’s Twitter feed:
We switched to likely voters for this week’s polls and as you might expect that’s not good for Dems
The post then goes on to link to a discussion of Illinois and Pennsylvania, two states where Democrats are likely to underperform this year.
Meanwhile, in the Rasmussen poll of Ohio, there is this note:
This is the first Rasmussen Reports Election 2010 survey in Ohio to include leaners. Leaners are those who initially indicate no preference for either of the candidates but answer a follow-up question and say they are leaning towards a particular candidate.
Early in any campaign, the numbers without leaners are generally more significant. Later in a campaign, the numbers with leaners matter more. After Labor Day, Rasmussen Reports will report the numbers with leaners as the primary indicators of the campaign
So be ready for whiplash.