Political experts use a variety of factors in predicting the outcomes of presidential elections, such as historical trends, candidate popularity, voter data and the political climate at the time of the election. Not all of experts, however, agree on the level of significance of each predictive factor.
In making initial predictions, historical voting trends are usually the first statistic cited. Political experts designate specific windows of time in which to demonstrate that one party or the other has dominated a presidential election following events historically similar to those in the current climate. As experts have pointed out, however, historical voting patterns are accurate only to the window of time reflected, not necessarily to the history of presidential elections in its entirety.
The political climate of the nation is also a primary factor in predicting the outcome of a presidential election. If the majority of the population is leaning more toward conservative ideals, then a conservative candidate is more likely to win an election and vice versa. Candidate popularity, though typically tied to political climate, is a key factor in predicting a presidential outcome. A particularly charismatic candidate is more likely to win an election regardless of his or her political platform, because he or she is able to draw voters to the polls who would not otherwise vote.