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More on Allocating Undecided Voters

October 20th, 2004, 4:00pm by Sam Wang


I’ve received lots of feedback on undecided voter assignment, much of it constructive. This has led me to rearrange the way the results are presented.

First: the calculation is now set to its old definition from two days ago. Many of you are very familiar with the raw (decided voters only) calculation by now. Switching back was suggested by many readers of various political persuasions. Whether people liked the direction of the outcome or not, many were uncomfortable with the mixing of current numbers and previous election outcomes. Also, this site has many calculations that are based on decided voters only, and it only adds confusion to redo those.

Second: the assignment of undecided voters is now done probabilistically, like the rest of the calculation. Past elections from 1956 to 1996 show a wide range of undecided breaks for the challenger: [+3 +6 +2 +1 +6 +0 +2 +4], median 2.5%, estimated SD 2.0% (analysis). This year may be unusual, though note in 1972 a break of 2% away from Nixon, at the height of the Vietnam conflict and after the invasion of Cambodia. Anyway, because the contribution is variable, the undecideds-assigned calculation (MATLAB script) takes this variation into account. The results are listed in the box above. This is my own current prediction. Also, the state probabilities are now given both with decideds only and with undecideds added. Thanks to Alan Cobo-Lewis and Rachel Findley for key discussions.

Third: There are now two maps (see box). The static image below is set with undecideds assigned.

Now, to the interesting bits. Look at the state probabilities. Because the undecideds could break evenly or for the challenger, many states are still toss-ups, including Florida and Ohio. The lingering uncertainty reinforces the idea that the election is close enough to be determined by turnout. Even if the undecideds break evenly, a 2% difference in turnout could change the result drastically, which you can see in one direction by comparing the maps. Have I mentioned before that I think turnout is important? Turnout is very, very important.

Whew, that was tiring. I think I need a wee dram!

Tags: 2004 Election

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