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Frequently Asked Questions

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Presidential Prediction

Where is the District of Columbia on the map and what are the probabilities associated with it?
The District of Columbia is not on the map though it is included in the statistical and probabilistic computations. At present, the probability of President Obama winning the District of Columbia is 1.00. This probability has not changed since our web site went live.

How are Maine and Nebraska handled?
Maine and Nebraska split their electoral college votes (4 and 5, respectively) based on their congressional districts. However, since congressional district state polling data is unavailable, these two states are treated like every other state (i.e., all or nothing).

Is a tie possible?
Yes, ties are possible. There are numerous combinations of states that can lead to a tie (269 Electoral College votes for both candidates). However, only a small fraction of such combinations are likely to occur.

What are Safe Electoral Votes?
Safe electoral votes are the votes that a candidate is almost certainly expected to win. Whenever a candidate has an 85% chance or greater of winning a state, the state's votes are considered safe.

What are the thresholds for the colors on the map?
States are considered Strong Democrat if the Democratic candidate has an 85% chance or higher of winning the state, Mild Democrat if the Democratic candidate has between a 60%-85% chance of winning the state, Mild Republican if the Republican candidate has between a 60%-85% chance of winning the state, and Strong Republican if the Republican candidate has an 85% chance or higher of winning the state. If neither candidate has above a 60% chance of winning the state, it is considered a Toss Up (also referred to as a battleground state).

Senate Prediction

How are Independents handled?
For the 2012 elections, there are two independent candidates running, Bernie Sanders in Vermont and Angus King in Maine. Sanders currently caucuses with the Democrats, and King is expected to do so. Because of this, the independent candidates can be included with the Democrats when computing the probability of one party achieving a majority. Columns labeled Dem + Ind report values when this is the case, while columns labeled Dem or Ind consider these two groups separately.

What are Safe Seats?
Safe seats are seats that a party is almost certainly expected to win. Whenever the party's candidate has an 85% chance or greater of winning, the seat is considered safe.

How are upcoming primaries handled?
In states where one or both primaries have not finished, the candidate currently leading in the polls is assumed to be the winner. Polling data comparing the leading candidates from both parties is then used to determine which party is likely to win the state.

House Prediction

How are Independents handled?
At present, no available polling data shows any races that are likely to be won by Independent candidates. Therefore, Independents are omitted from the House calculations.

Why do the House results change so little?
There are two major reasons why the House results remain fairly constant. First, only a handful of House races are truly competitive, so many of the districts are guaranteed to one party or the other. Second, even for the the competitive races, polling data is not widely available. Without new polls, the results will not change.

How are the map colors determined?
The states on the House map are colored in proportion to the expected number of representatives from each party. As an example, consider a state with D districts, where the expected numbers of representatives from Parties A and B are given by x and 10-x, respectively. The colors are determined based on the proportions x/D and (10-x)/D and the thresholds used on the presidential site.

Is a tie possible?
The total number of representatives in the House is 435. Since the current model does not consider Independent candidates, there is no way for the two parties to have an equal number of House seats.


Why do some probabilities not add up to 1.00?
Not all probabilities will add up to 1.00 because of slight round-off error in the computations and the need to truncate the numbers for display purposes.

How can the predictions on different web sites be different?
Each web site uses their own set of algorithms and methodologies. In any close election (as this one appears to be), one site may predict the Democratic candidate as the winner, while another may predict the Republican candidate as the winner. Since our methodology only uses state polling data and ignores popular vote polling data, it may seem that one candidate is gaining in popularity, yet their probability of winning the election does not change significantly or moves in a direction contrary to what one would expect. For our methodology, only when there are shifts in state polling data will the results change the prediction measures.

Where can I find results from previous elections?
Our prediction results for the 2008 presidential election can be found here.

Other Prediction Sites Polling Sites

University of Illinois
at Urbana-Champaign

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