Aggregating Predictions for 2008

On October 7th, a peer of mine collected 20
surveys from self-selected (volunteered) members of the political science
department (from first year graduate students to professors) on an electoral
challenge.  The survey presented seventeen
different questions in regards to electoral outcomes and those who were able to
predict the most accurately 14 of the 17 questions (with 3 of the questions
serving as tie breakers) win an undisclosed prize for the top performer.  There is no prize awarded for second place.

This is neither a random sample nor a sample of electoral
experts, but instead represents a combination of strategic and sincere beliefs
of the upcoming election (grounded in the week of 10/7/08) by individuals who
are quantitatively and politically savvy. 
Given this caveat and framework, there are a few potentially interesting
results that might intrigue readers since are one week away from election day.

The national election results are not overly exciting to put
in graph form.  18 of the 20 (90%)
entries suggested that Obama would win. 
One of the tie-breakers asked for a prediction of the spread.  The question asked for a spread in percent,
but an entry contained 3,000,000 as an answer; I gather that this prediction is the number of votes cast for the particular candidate. 
I converted this to  2% given the turnout of 2004 having
roughly 125 million voters and we expect a higher turnout this year.  Given McCain
spreads a negative value (to move away from the absolute value that is
currently coded), the spread of the predictions can be seen in the below
table.  The mean prediction is 4.87
(positively in Obama’s favor) with a standard deviation of 2.66.

Magin of Victory


The Battleground States

The next table shows the results for the six battleground
states tested.  Generally, it appears
that there is favoritism towards Obama in four of the states.  North Carolina appears to be clear McCain
ground and Nevada has a bit of uncertainty around the prediction.   Technically, this is the same variance that
North Carolina has and should be regarded as the same probability of either,
but I believe, given the other results, that Obama might be over-favored in
this sample.



Senate Races



Four races were questioned and the most contentious race was
Begich-Stevens.  If this question was
asked today, I believe the distribution would be more skewed, leaving the Minnesota race as the most likely for an upset. 
The histogram below shows the predicted Democrat gains in the Senate.  The data provide a mean of 4.75 seats witha  standard deviation of 1.8.



House Races



The four races here are a bit tighter.  This may occur from actual close races for
the house or increased general ignorance about the state of the races.  As such, New York’s 26th and
Connecticut’s 4th are not deterministic.  The predicted Democrat gains in the House has
much more variance, as would be obvious, than the Senate.  However, 25% of the respondents belived 15 to
be likely.  The mean was just under 13 seats
for the Democrats.


The summary statistics are relatively simplistic and do not leave room for causal interpretation.  However, given that it is an aggregate of predictions, it is an interesting poll of sorts. You can view the data that I have here if you are so inclined: Download election_prediction.csv

Michael A. Allen

About Michael A. Allen

Michael is an Assistant Professor in Political Science at Boise State University with a focus in International Relations, Comparative Politics, and Methodology (quantitative and formal). His work includes issues related to military basing abroad, asymmetric relations, cooperation, and conflict. He received his Ph.D from Binghamton University in 2011.

One Reply to “Aggregating Predictions for 2008”

  1. On Wed. you should compare the performance of the IR and Comparative-American folks. I predict IR faculty and grad students will prevail.

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