Presidential Election - Update 3

I am continuing to use the average of polls for the 18 battleground states from the last week or so as reported by RealClear Politics. I believe this makes the analysis more robust than relying on just the latest poll results.

Here is the latest update to my simulation-based predictions of the presidential election outcome using data as of 12:05 AM, October 29.

SCENARIO	Kerry electoral votes	Kerry win probability
Undecided voters split between Kerry and Bush	259	29.03
Undecided voters favor Kerry 3:2	275	59.16
Undecided voters favor Kerry 2:1	286	77.58

Scroll down for a graph showing the projected distribution of Kerry's electoral votes for the scenario where undecided voters favor Kerry 3:2. The blue bars denote the outcomes corresponding to a Kerry victory. As in my previous post, I am going with this scenario as my "bottom-line" prediction.

Details of the model and other assumptions can be found in my Oct 21 post titled "Presidential Election" - accessible from the "Previous Posts" menu on the right.

I will update this table with my final prediction on Monday (11/01).

Until then, 10-4.

Distribution of Kerry electoral votes - Update 3 

Presidential Election - Update 2

I have made one modification to my model. Instead of using the latest poll results for the 18 battleground states, I now use the average of polls from the last week or so as reported by RealClear Politics. Hopefully, this makes the analysis more robust.

One other caveat - I have excluded the CNN/USAT/Gallup poll from 10/21-24 for Florida as it appears to be an outlier. They show Bush+8, while the other polls show Bush+1.2, Bush+4, Kerry+3, Tie, Kerry+2, Tie.

Here is the latest update to my simulation-based predictions of the presidential election outcome using data as of 11:55 AM, October 27.

SCENARIO	Kerry electoral votes	Kerry win probability
Undecided voters split between Kerry and Bush	261	35.08
Undecided voters favor Kerry 3:2	278	66.16
Undecided voters favor Kerry 2:1	290	81.84

Scroll down for a graph showing the projected distribution of Kerry's electoral votes for the scenario where undecided voters favor Kerry 3:2. The blue bars denote the outcomes corresponding to a Kerry victory. As in my previous post, I am going with this scenario as my "bottom-line" prediction.

Details of the model and other assumptions can be found in my Oct 21 post titled "Presidential Elections" - accessible from the "Previous Posts" menu on the right.

I will update this table on Friday (10/29) and finally on Monday (11/01).

Until then, 10-4.

Distribution of Kerry electoral votes - Update 2

Presidential Election - Update 1

In my last post, I presented assumptions behind a simulation-based model for predicting the outcome of the presidential election and some preliminary results. Here is the update using data as of 11:07 AM, October 25:

SCENARIO	Kerry electoral votes	Kerry win probability
Undecided voters split between Kerry and Bush	260	35.72
Undecided voters favor Kerry 3:2	279	66.48
Undecided voters favor Kerry 2:1	292	85.52

Scroll down for a graph showing the projected distribution of Kerry's electoral votes for the scenario where undecided voters favor Kerry 3:2. The blue bars denote the outcomes corresponding to a Kerry victory. I am going with this scenario as my "bottom-line" prediction.

For the detail-oriented, here is a link that provides an analysis of past elections suggesting that undecided voters tend to favor the challenger .

I will keep updating the table and the figures on a daily basis, time permitting.

Until then, 10-4.

Distribution of Kerry electoral votes - Update 1 

Presidential Election

Pollsters and pundits from both sides of the political spectrum agree that the presidential race is too close to call. Voter preference in many toss-up states keeps fluctuating daily between President Bush and Senator Kerry within the polling margin of error. Given this uncertainty, how useful are predictions that rely only on the raw percentages in favor of each candidate and ignore the statistical margin of error? How does one make a prediction about the overall outcome that takes into consideration (a) the limited sample size used in most polls, and (b) the sampling error of the poll itself?

Using data from 2.004k.com as reported by Andrea Moro (who also has links to other probabilistic prediction websites), I have developed a simulation-based prediction of the outcome of the presidential election. Here is how my model works:

• I first allocate undecided voters to either the incumbent or the challenger on a state-by-state basis.
  
• Then, for each state, I simulate the likely percentage of Kerry votes assuming it follows a normal distribution with (a) mean based on the poll results plus undecided allocation and (b) standard deviation based on the polling error.
  
• The winner for each state is allocated all of the state's electoral votes.
  
• The results are tallied for 5000 simulations to provide the average electoral votes for Kerry and also the probability of Kerry winning more than 270 electoral votes.

Based on data as of 9 AM, Oct 21, the results are as follows:

SCENARIO	Kerry electoral votes	Kerry win probability
Undecided voters split between Kerry and Bush	260	25.72
Undecided voters favor Kerry 2:1	295	87.84

Scroll down for a graph showing the projected distribution of Kerry's electoral votes for these two scenarios. The blue bars denote the outcomes corresponding to a Kerry victory. It's fascinating to note how sensitive the predictions are to assumptions regarding the behavior of undecided voters. I will keep updating the table and the figures on a daily basis, time permitting.

Until then, 10-4.

Distribution of Kerry electoral votes 

Hello, World!

"The only certainty is uncertainty" - so said Pliny the Elder when the Romans held sway. And we have indeed come a long way from Pliny's negativity because uncertainty has ceased to exist - especially in matters of public policy and fiscal management.

In this blog, I will try to point out various instances where a simple consideration of uncertainty can suggest a different insght about the problem at hand and/or decisions to be made.

Why do I feel qualified to undertake this venture? Well, I have been wrangling with uncertainty and its impacts on the analysis of energy and environmental problems for over a decade. It seems to me that the approaches we use in science and engineering can readily be extended to other areas - if only we get people's attention. So, here goes!

In the next day or so, I will be posting a prediction of electoral college votes for the 2004 presidential election that takes into acount the uncertainty in current state-by-state polling numbers. As time permits, related topics may find their way into this blog.

Before signing off, let me just note that recognizing uncertainty does not mean one has to plan for the most optimistic or the most pessimistic outcomes. As Bertrand Russel has eloquently pointed out, "When one admits that nothing is certain, one must, I think also add that some things are more nearly certain than others." (Am I an Atheist or an Agnostic?)

On that note, 10-4.