Decision Desk HQ Election Pulse

The Decision Desk HQ (DDHQ) Election Pulse (EP) provides real-time updates on election night, providing insight into the likelihood of results as votes are reported. The EP starts with a pre-election forecast and continually adjusts it based on incoming vote counts and patterns. It incorporates both reported votes and estimates of remaining uncounted ballots to refine its predictions, providing a dynamic look at each race as election night progresses. A previous model, focused primarily on primary elections, was published in the Harvard Data Science Review (HDSR) in October 2024. The general election version contains additional logic based on the findings of this earlier work. Model predictions are displayed with a delay of X minutes compared to the live version.

Viewers can follow Election Pulse on the Decision Desk HQ website for live election results.

Coverage of the Wahlpulse race

The DDHQ Election Pulse operates in real time for most nationwide elections, including presidential and Senate races, but does not cover many safe states where incoming data streams do not provide enough information to make accurate predictions. For states like AZ/NV, predictions are not expected to change significantly on election night because many votes are not counted until after election night. Topline estimates for most states will be updated throughout the night, but are expected to be finalized around 3-4 a.m. ET when voting reports are completed for the evening.

Topline probabilities and government control

DDHQ Election Pulse provides real-time “topline” probabilities for several critical outcomes:

1. The probability of either Trump or Harris winning the Electoral College.
2. The likelihood that Democrats or Republicans will win control of the U.S. Senate.
3. The likelihood of Democrats or Republicans winning control of the U.S. House of Representatives.

These probabilities are based on racial models and electoral rolls for the Senate and Presidential elections, while House estimates are based on electoral rolls. As with the race-specific estimates, toplines are expected to stop updating once coverage for the night ends around 3-4 a.m. ET.

Independence from race calls

While the EP provides valuable insights in real time, it operates independently of the DDHQ race call process. A high probability of victory in the EP does not automatically trigger a Race Call, and the Race Call Team may declare a winner based on information not considered by the EP. The Race Call team has access to direct communications with election officials and other proprietary data that enables more informed decisions that may occasionally differ from the EP's predictions.

Interpretation of changes in electoral momentum

The EP assesses candidates' performances relative to pre-set expectations, rather than focusing solely on vote counting. For example, even if a candidate receives raw votes in a particular update, they may lose ground in the EP if their performance falls short of predicted benchmarks. This enables a differentiated view of the electoral dynamics that goes beyond simple vote numbers. The model takes into account geospatial and demographic data and detects patterns in areas with similar voter profiles.

Adaptation to report and ballot types

The DDHQ Election Pulse is designed to handle complex voter reporting patterns, particularly those caused by absentee or absentee voting. As voter behavior has changed in response to new election laws, particularly with the increase in mail-in voting, election night vote counts (particularly early in election night in partially reported counties) often do not reflect the final result. For example, a candidate who initially appears to be losing may still be favored in the EP if late voting is expected to lead to a postponement of the race. The EP adapts to these patterns, taking into account voting types and timing of reporting, to provide a clearer picture of the race.

Special Considerations for Arizona and Nevada

In Arizona and Nevada, where a large portion of votes are received by mail after Election Day, the transition between early and late returns can be unpredictable. As such, the models displayed here are based primarily on pre-election prioritizations and may not be significantly updated on election night. Due to the fluidity of vote counting in these states, forecasts are unlikely to change significantly Tuesday evening.

To account for this, the topline probabilities are influenced by prior polling and historical correlations to ensure the projections are accurate even without informative election night voting data in Arizona and Nevada. In states with EP models, front-end forecasts remain static until voting begins reporting.