Map Algorithm Explained

Based on the results of the 2004 election, the algorithm used to generate the map has been modified. The new algorithm did better in 2004. Here is the exact algorithm:

1. The most recent poll in every state is always used.
2. If no other polls were taken within a week of the most recent one, only the most recent poll counts.
3. If one or more polls were taken within a week of the most recent, all of them are averaged.

This algorithm smoothes out fluctations better and produces fewer wild swings and gives a better overall result. You can see which polls were used by putting the mouse on a state. The Source field tells which polls are used and gives the final date of the final poll used. If multiple polls were used, the first five characters of each pollster are listed and the pollsters are separated by a "+" sign.

A consequence of this new algorithm is that in the "News from the Votemaster" section, a new poll may be reported but the map gives a different result. This effect is always due to multiple recent polls being averaged. You will see tthat this is the case by looking for the "+" sign used to separate multiple pollsters in the Source field of the pop-up box. Another consequence of this algorithm, is that this site may give slightly different results from other polling sites, each of which uses its own algorithm, sometimes a far more complex one.

Why a look-back window of 1 week? It is admittedly arbitrary. If the window is too short, the results gyrate wildly as different polls use different methodologies . If the window is too long, genuine shifts in public opinion take too long to show up. The choice of 1 week is based on my now-extensive experience with examining polling data. Public reaction to news events often takes several days to take effect as people often change their opinions after talking to friends, coworkers, and relatives.