- Previous result: State i’s result from the previous election.
- Prior national polls: Average of all national head-to-head matchup polls taken in month X before the election.
- Home state: 1 if state i is the home state of the Democratic candidate, -1 if it’s the home state of the Republican candidate, and 0 otherwise.
- Regime age: The number of terms the current party in the White House has occupied.
The model generates forecasts of state-level outcomes using the following vote equation:
Vi = A + b1
Previous resulti + b2
Prior national polls + b3
Home statei + b4
The forecast of the national popular vote is then calculated by weighting each state by its proportion of the total number of votes cast in the previous election.