The Mason-Dixon polling organization has released a raft of polls in key battleground states in the past two weeks. Mason-Dixon is a reputable organization, but if you?ve been getting the feeling that their results this year are a bit skewed, you?re correct. I compared the results of Mason-Dixon?s October polls with the average of all other polls released in October in the same states. So far this month, Mason-Dixon has released 16 polls in 14 battleground states. Here are the comparisons. The number shown is the difference between the percentage of likely voters supporting George Bush and the percentage supporting John Kerry. A negative number means that Bush was trailing. The number in parentheses is the number of October polls in the state.
Average Bush
of All Mason-Dixon
State Mason-Dixon Other Polls Advantage
Colorado +7.5 (2) +4.5 (6) +3.0
Florida +3.5 (2) +0.3 (10) +3.2
Iowa +6.0 (1) +0.8 (7) +5.2
Michigan -1.0 (1) -4.2 (5) +3.2
Minnesota +2.0 (1) -3.5 (4) +5.5
Missouri +5.0 (1) +4.7 (3) +0.3
Nevada +10.0 (1) +5.5 (2) +4.5
New Hampshire +3.0 (1) -2.0 (8) +5.0
New Mexico +5.0 (1) -2.0 (4) +7.0
Ohio +1.0 (1) -1.3 (11) +2.3
Oregon -1.0 (1) -4.4 (5) +3.4
Pennsylvania -1.0 (1) -3.8 (9) +2.8
West Virginia +5.0 (1) +2.0 (1) +3.0
Wisconsin 0.0 (1) -0.2 (1) +0.2
14 State Average +3.2 ;(16) -0.3 (76) +3.5
In all 14 states, Mason-Dixon?s polls were more favorable to George Bush than the average of all other polls. Based on Mason-Dixon?s polls, Bush was leading in 10 states, Kerry in only 3. Based on the average of all other polls, Bush was only leading in 6 states, Kerry in 8. Given the number of states and the number of polls included in this analysis, this difference is quite striking. In some states, such as Missouri and Wisconsin, the difference between Mason-Dixon and the other polls was trivial. However, in the crucial battleground states of Iowa, New Hampshire, and New Mexico, the difference was large enough to give a rather different impression of the state of the presidential race. Moreover, since the Mason-Dixon polls are often sponsored by prominent media outlets, it is likely that their results have been more widely publicized than those of most of the other state polls.
I have no explanation for why Mason-Dixon?s polls in the battleground states have been consistently more favorable toward George Bush than other polls in the same states. Perhaps the election results on November 2nd will prove that they were more accurate than their competitors. However, it is worth noting that the average of all of the other state polls, a dead heat between George Bush and John Kerry, is closer to what most of the national polls have been showing recently in the battleground states.
