These 13 sentences led a professor to predict Trump’s win

As many people in the country breathlessly checked the latest polling numbers ahead of Tuesday’s election, Allan Lichtman, a history professor at American University, had already predicted the outcome with an entirely different system.

Lichtman uses a series of 13 “keys,” which are true/false statements that he says can help predict whether the incumbent party will remain in the White House. For each of these statements, a “true” statement favors the incumbent party, but enough “false” statements portend their defeat in a presidential election. This model, he told the Washington Post in September, predicted that Trump would win the presidency.

His model has accurately predicted the winner of every popular vote since 1984. This time, he predicted Trump would win the popular vote and the election — and although the popular vote is now projected to go to Democratic presidential nominee Hillary Clinton, the Electoral College was in Trump’s favor, winning him the presidency.

Lichtman outlines the historical basis for the keys in his book, “Predicting the Next President: The Keys to the White House 2016.”

Here are the keys:

1. Party Mandate: After the midterm elections, the incumbent party holds more seats in the U.S. House of Representatives than after the previous midterm elections.

2. Contest: There is no serious contest for the incumbent party nomination.

3. Incumbency: The incumbent party candidate is the sitting president.

4. Third party: There is no significant third party or independent campaign.

5. Short-term economy: The economy is not in recession during the election campaign.

6. Long-term economy: Real per capita economic growth during the term equals or exceeds mean growth during the previous two terms.

7. Policy change: The incumbent administration effects major changes in national policy.

8. Social unrest: There is no sustained social unrest during the term.

9. Scandal: The incumbent administration is untainted by major scandal.

10. Foreign/military failure: The incumbent administration suffers no major failure in foreign or military affairs.

11. Foreign/military success: The incumbent administration achieves a major success in foreign or military affairs.

12. Incumbent charisma: The incumbent party candidate is charismatic or a national hero.

13. Challenger charisma: The challenging party candidate is not charismatic or a national hero.