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:
- Popular vote share - this is what most people think of as the “popular vote.”
- 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.
- 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.