Introduction: Electoral Results and Tipping Points

Introduction

Before we get into prediction, it will be helpful to get some background on the history of elections in the United States. Let’s start with a relatively simple question: how do election results change year to year? There are several ways to measure the results of an election:

1. Popular vote share - this is what most people think of as the “popular vote.”
2. Two party popular vote share - this exculdes third party candidates, which have not had a major impact on presidential election outcomes since before World War II. However, at a state level, third parties can have a signficant impact, as there have been relatively recent instances of third party candidates winning small numbers of states and electoral votes.
3. Electoral votes - awarded on a state by state basis, this is what candidates have to win to win the presidency. I’ll take a closer look at what states seem matter (by one definition of “matter”) later in this entry.

Popular Vote Share

Because the presidential election is determined on a state by state basis, it’s good to start looking at some maps. For now, I’ll stick to the two party vote share, becuase intuitively that’s what matters for election outcomes; because of the weakness of third party campaigns since WWII, whoever wins between the Republican and Democrat almost always wins the state and therefore the electoral votes.