Two new polls released today showed what was apparently contradicting trends for President Obama and Republican presidential nominee Mitt Romney. A Gallup poll released this morning showed Obama with a five point lead on Romney (50% to 45%). However, this afternoon Pew Research released a poll that showed Romney with a four point lead (49% to 45%) over Obama. The apparent paradox could be explained by the timing of the two polls as well as their sampling methods.
First, Gallup’s poll includes all registered voters, which tends to favor Democratic candidates. Pew’s poll, on the other hand, only includes likely voters which may have helped Romney. A likely voter model, if done correctly, is more accurate since all not all registered voters actually show up to the polls.
The second factor that may explain the difference in numbers is the timing of each poll. Gallup’s poll included interviews conducted from October 1 to October 7. Some of Gallup’s interviews were conducted before last Wednesday’s presidential debate, which is largely attributed with giving Romney his increased support. While some might argue this makes Gallup’s numbers less accurate, the long date range of Gallup’s tracking poll may actually reflect reality better, since Gallup is able to smooth any extreme swings in support for or against either candidate.
Pew’s polling was conducted solely after the presidential debate from October 4 to October 7. Again, some might argue that the more recent interviews make Pew’s poll more accurate. However, it is also possible that Pew caught voters at the height of the “Romney bump” from which Romney is currently coming down.
Other polls also suggest that Romney is not doing as well as the Pew poll currently shows. Rasmussen Reports, which tends to favor Republican candidates, currently has the national race tied after having Romney with a lead in the days after the debate. Rasmussen also has Obama ahead of Romney in Colorado and Iowa. Both of the Rasmussen state polls were conducted after the debate, and both show Romney actually losing ground on Obama after the debate as opposed to gaining ground. Public Policy Polling also released a poll showing Obama three points ahead in Virginia (50%-47%). EPIC-MRA and Baydoun/Foster released two separate polls which show Obama maintaining a lead in Michigan, albeit by a smaller margin.
However, readers should take not put too much stock into any one poll, even polls down by reputable organizations like Pew and Gallup. Instead, the best analysis involves interpreting all the polls to see overall trends for each candidate. Looking at all the polls that were released today, it is clear that Romney made significant gains after his superior debate performance, but Obama still holds on to leads in many key states, and there is some evidence to suggest that Romney’s momentum may be subsiding over time.