please download the full forecast PDF document here
shortened abstract below:
The Primary Model
87%-99% Certain Trump Will Be President
Primaries Predict Election Winner -- Cycle Also Favors GOP —
Forecast Model Batting 5 for 5 (since 1996)
by Helmut Norpoth
It is 87% to 99% certain that Donald Trump will win the presidential election on November 8, 2016; 87% if running against Hillary Clinton, 99% if against Bernie Sanders.
These predictions come from primarymodel.com
It is a statistical model that relies on presidential primaries and an election cycle as predictors of the vote in the general election.
Winning the early primaries is a major key for electoral victory in November. Trump won the Republican primaries in both New Hampshire and the South Carolina while Hillary Clinton and Bernie Sanders split the Democratic primaries in those states.
What favors the GOP in 2016 as well, no matter if Trump is the nominee or any other Republican, is the cycle of presidential elections. After two terms of Democrat Barack Obama in the White House the electoral pendulum is poised to swing to the GOP this year.
In a match-up between the Republican primary winner and each of the Democratic contenders, Donald Trump is predicted to defeat Hillary Clinton by 52.5% to 47.5% of the two-party vote. He would defeat Bernie Sanders by 57.7% to 42.3%.
For the record, the PRIMARY MODEL, with slight modifications, has correctly predicted the winner of the popular vote in all five presidential elections since it was introduced in 1996. In recent elections the forecast has been issued as early as January of the election year.
Presidential elections going back as far as 1912 are used to estimate the weight of primary performance. It was in 1912 that presidential primaries were introduced. That year the candidate who won his party’s primary vote, Woodrow Wilson, went on to defeat the candidate who lost his party’s primary vote, William Howard Taft. As a rule, the candidate with the stronger primary performance wins against the candidate with the weaker primary performance. For elections from 1912 to 2012 the PRIMARY MODEL picks the winner, albeit retroactively, every time except in 1960.
For elections prior to 1952 all primaries were included. Beginning in 1952, only the New Hampshire Primary has been used, as a rule. South Carolina has been added to gauge primary performance this year. Hillary Clinton enjoys strong support in a large group of voters, African-Americans, who are few in numbers in New Hampshire. Her combined performance in New Hampshire and South Carolina gives her a higher primary score than Sanders. As a result, in the general election Clinton fares less badly against Trump than does Sanders.
An earlier forecast, which garnered much notoriety, predicted a Trump victory over Clinton with 97% certainty. That prediction was made before the Democratic primary in South Carolina was held and relied on polling reports for that state. Clinton wound up beating Sanders by a much bigger margin than was indicated by pre-primary polls. Still, it is 87% certain that Trump will defeat Clinton in November.
It is possible, of course, that the Republican Party will not nominate Trump as its presidential candidate. If the nomination were to go to Marco Rubio instead the PRIMARY MODEL would predict:
It is 86% certain that Hillary Clinton will defeat Marco Rubio. Clinton will get 52.4% and Rubio 47.6% of the two party vote.
According to the model, Ted Cruz or any other candidate (except Trump) would fare the same way against Clinton.
In the event that the Democrats nominate Bernie Sanders instead of Hillary Clinton, while the GOP nominates Marco Rubio, the PRIMARY MODEL would predict:
It is 89% certain that Marco Rubio will defeat Bernie Sanders. Rubio will get 52.8% and Sanders 47.2% of the two party vote.
According to the model, Ted Cruz or any other candidate (except Trump) would fare the same way against Sanders.