Because it’s pertinent to our recent discussion on undecideds, I want to provide a brief overview of the movement of undecideds in Pennsylvania in the last two weeks. In looking at this data, don’t forget the ecological fallacy issue – we can’t be sure of individual level movement based on aggregate data. With that in mind, Muhlenberg College conducts the only daily tracking poll in Pennsylvania. Since Oct. 14, Obama has gone from 51% to 52%, a gain of 1%. McCain has gone from 38% to 44%, a gain of 6%. The number of “undecideds” or “others” has dropped from 11% to 5%. This is consistent with – but not proof of – undecideds/others breaking for McCain at about 5-1. Even if this is true, however, and the remaining 5% break for him at this rate, Obama will still win the state. For McCain to spring the upset, he needs to see some slippage in Obama’s support rather than simply relying on winning the undecideds. And this holds true at the national level as well.
Keep in mind that this is all based on one tracking poll with all the requisite warnings I have given you regarding relying on a single poll, random variations, margin of error, etc. Moreover, Pennsylvania’s demographics do not mirror the nation’s, so one should not necessarily extrapolate trends from that state to the overall race.