In the weeks leading up to last Tuesday's election, one of the ways in which those on the right convinced themselves that Romney was going to win, despite what the polling was saying, was to make the claim that undecided voters tend to break for the challenger on election day.
That assumption could not be further from the truth. To prove it, I took the final average for each swing state on Real Clear Politics and compared it to the actual result on election day. Almost without exception, Obama did better than the projected numbers while Romney did considerably worse.
STATE PROJECTED ACTUAL DIFFERENCE
CO 1.5% 4.7% +3.2 Obama
FL -1.5% .9% +2.4 Obama
IA 2.4% 5.6% +3.2 Obama
NV 2.8% 6.6% +3.8 Obama
NH 2.0% 5.8% +3.8 Obama
OH 2.9% 1.9% -1.0 Obama
VA .3% 3.0% +2.7 Obama
WI 4.2% 6.7% +2.5 Obama
NC -3.3% -2.2% +1.1 Obama
Thus, as you can see, in eight of the nine "battleground" states, Obama received a higher percentage of the actual vote on election day than poll averages indicated he would.
So, the next time someone tries to convince you that undecideds break for the challenger on election day, keep these basic facts in mind.