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With only three days left, Obama’s reelection chances have rebounded to 96%

Nov03
2012
4 Comments J. Brian Adams Written by J. Brian Adams

Despite the near tie in the latest polling of the nationwide popular vote, Obama appears poised to remain in the White House for four more years.

Running our simulation model with the last set of weekly polls before Tuesday’s election, President Obama once again has moved up to a near certain win for the electoral vote. As of November 2, our model predicts a 96% chance of reelection with Governor Romney’s chance of unseating the President falling back to 4%. While there is still buzz about the possibility of an electoral college tie – and the resulting President Romney and Vice-President Biden – that probability has also fallen to near zero.

At this point, Obama can claim 199 electoral votes as near certainties to Romney’s 159. When the likely wins are included Obama’s total rises to 226 and Romney’s to 173. If you include all of the states that are currently leaning for reelection, the President climbs well past the needed 270 to 332 electoral votes.

The challenge for Governor Romney is to retake several of the states that are leaning blue. The most likely of these is New Hampshire followed by Ohio but at a total of 22 electoral votes that only drops Obama to 310. If Romney can also win both Virginia and Florida he raises his total to 272 and a win – but even losing New Hampshire’s four votes from that mix turns his win back to a loss.

At this point our model is predicting an electoral college vote of 314 for President Obama and 224 for Governor Romney – a buffer of 45 votes. While this is the most likely outcome, the next most likely possibilities have even higher totals for the President. In fact the top fifty percent of the outcomes are all above 294 electoral votes.

A common saying by candidates is that the only poll that counts is the one on election day. And while an upset is still a possibility, that possibility currently appears to be quite unlikely.

Posted in Polling - Tagged campaign, polling

President’s Reelection Chances Rebound with a Rise to Above 96%

Jul19
2012
1 Comment J. Brian Adams Written by J. Brian Adams

With last week’s release of eight new statewide polls the probability of President Obama being reelected has rebounded eight points to a new high of over 96%. Governor Romney’s probability of winning has similarly dropped eight points to 3%. These percentages represent the probability of each candidate receiving at least 270 electoral votes. The probability of a tie remains at less than 1%

These results are based upon a statistical model that uses currently available opinion polls for each of the fifty states and the District of Columbia. It analyzes these polls determining each possible outcome with its likelihood of occurring.

Of the eight states involved in the new polls, five – New Mexico, Virginia, Maine, North Carolina, Pennsylvania, and Wisconsin – have increased their support for the President. Two states – Florida and North Dakota – show increases for Governor Romney. Polls from Virginia and North Carolina indicate strong increases for Obama with both states moving from leaning Romney to now leaning Obama.

Florida which had been showing a fractional advantage towards Obama remains close but the slight advantage has now moved to Romney.

There are still three states, Iowa, New Hampshire, and Tennessee that are in the tossup category. Tossup states are the states in which there is not a statistically clear winner.

States that are leaning Obama are currently CO, MI, NV, NC, OH, and PA.
The states that are leaning Romney are FL, IN, KS, KY, SC, and SD.

The states that are likely wins for the President are ME, NM, OR, VA, and WI.
MO, and MT are likely wins for Governor Romney.

The final category are those states that would be considered statistically certain outcomes.

For President Obama these are CA, CT, DE, DC, HI, IL, MD, MA, MN, NJ, NY, RI, VT, and WA.
For Governor Romney the certain win states are AL, AK, AZ, AR, GA, ID, LA, MS, NE, ND, OK, TX, UT, WV, and WY.

The box plots show the distribution of predicted electoral votes for each candidate over the past seven weeks. The center rectangle includes the middle 50% of the outcomes while the whiskers cover the most likely 99.5% of outcomes. The green line marks the 270 electoral vote cutoff needed to win the election.

The time series plot tracks the trend in the probability of winning since the middle of May.

Box Whisker Plots for Possible Electoral Votes

Comparison of Predicted Electoral Vote Outcomes for President Obama and Governor Romney

Trend of Probabilities of Receiving 270 or More Electoral Votes

Posted in Polling - Tagged electoral college, polling, statistical model

Latest Polls Indicate Probability of Reelection Down But Still Strong

Jul09
2012
Leave a Comment J. Brian Adams Written by J. Brian Adams

With the release of the latest statewide polls President Obama has an 88% chance of winning reelection as compared to Gov. Romney’s 11% with a 1% chance of a tie.

These results are based upon an analysis of the combinations of possible results using Monte Carlo techniques. This simulation model combines the estimated percentage of votes that each candidate is expected to receive while further taking into account the percentage of the electorate that may still be undecided.

With each run a number of electoral votes is predicted for each of the fifty states and the District of Columbia. A simulated winner of the election is thus determined. By running the model millions of times, the technique estimates the percentage of the simulated elections that each candidate wins and thus the probability of winning the election.

The input data for the simulation model is collected from the most current public opinion polls that are available for each state. Since new polls are conducted almost daily, the probabilities frequently change.

Of course the polls only reflect the electoral vote outcome for a single state so while the results do vary, the magnitude a particular change is dependent upon the size of the state. For example, a change in the public polls for Florida with its twenty-nine electoral votes has a far larger impact on the outcome of the national election than does a change in Delaware with its three electoral votes.

The model has been run weekly since the middle of May. With the latest set of polls President Obama’s probability of winning has dropped slightly from 93% in the previous week to 88% this week. With this drop for the President, Governor Romney’s probability of winning the election has risen from 6% the previous week to just over 11%. The probability of a tie – both candidates receiving 269 electoral votes – has also risen to just under 1%.

As events unfold over the next five months the polls will reflect the opinions of the electorate to those events. With the changing polls the probability of a particular candidate winning the election can change as well. If a third party candidate enters the race and is included in the polls then that candidate’s impact can also be modeled.

While polls provide a snapshot of the opinion of the electorate, this statistical modeling technique can use these opinions to make quantitative predictions about the November outcome.

Comparison of Predicted Electoral Vote Outcomes

Trend of Probabilities for Winning the November Presidential Election

Posted in Polling - Tagged opinion polls, statistical model

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G. Terry Madonna, editor