In the book, The Democratic Trend Phenomenon, the author, Anthony E. Fairfax, proves that the popular vote percentage for President Barack Obama could have been predicted in 2004 with a fair amount of precision. In fact, one of the most interesting discoveries of the Democratic Trend involves projecting the popular vote percentage for the Democratic candidates as well as who Fairfax calls "Non-Democratic candidates." Because of the phenomenon, the percentages of the popular vote of the Democratic candidates and Non-Democratic candidates combined also tend to trend in a linear fashion.
Projecting the trend for the 2008 election yields 51.1% (+/-2.7%) of the vote for Senator Barack Obama while 48.9% (+/-2.5%) is divided amongst Senator John McCain and the other Non-Majority Party candidates. The actual results yielded Obama with 52.8% with 47.2% for the Non-Democrats. Thus, the predictions from the Democratic Trend was off by -1.7%, with an error percentage of -3.4%. Not too bad considering the prediction was made four years in advance.