The electoral-cycle model by Helmut Norpoth predicts the election outcome based on electoral history. In particular, it uses the vote of the two most recent elections as predictor variables in a linear model, which has been estimated based on data from all elections since 1828. The model’s vote equation reads as
V = 49.2 + 0.525
Vt-1 – 0.474
where V is the incumbent party’s popular two-party vote,
Vt-1 is the incumbent party’s popular two-party vote in the last election, and
Vt-2 is the incumbent party’s popular two-party vote in the second to last election.
The model reveals the following pattern:
- There is a boom-bust cycle of electoral fortunes
- The cycles are irregular in length (period) as well as width (amplitude)
- The average length of a cycle is estimated as 5.2 terms
- The White House party can expect to stay in office 2.6 terms
For 2016, the electoral-cycle model predicts the Democratic candidate to achieve 48.6% and the Republican candidate to achieve 51.4% of the popular two-party vote.
Norpoth, Helmut (2014). The electoral cycle. PS: Political Science & Politics, 47(2), 332-335.