Polls Favoring Romney
Three out of the four polls that had Romney in the lead used samples that consisted exclusively of self-identified likely voters, and narrowing samples in this manner is controversial. Proponents argue that results are more likely to fall in line with actual election data when only those who state their willingness to vote are polled, while opponents argue that many people change their minds about voting, and polling likely voters when the election is months away needlessly limits the sample. There is no doubt, however, that these polls favored Romney, since all the “likely voter” surveys conducted thus far in May gave him the victory.
Another similarity among the polls that favored Romney is in the sample size – polls in which the GOP candidate lead have smaller sample sizes, ranging from 500 to 1000 respondents, and three out of the four polls used sample sizes of 800 or less.
Polls Favoring Obama
The polls that favored Obama had larger and more general samples, with sizes ranging from 856 to 3050 – larger samples tend to be more statistically accurate, with smaller margins of error. These polls did not focus on members of the population that described themselves as likely to vote: three of them consisted of registered voters, and one simply polled adults without asking whether they are registered, or likely to vote.
Interpreting the Aggregate Poll Results
The race between Obama and Romney has clearly tightened during the month of May, but observers debate which candidate has the edge. Polling purists, who believe that large, diverse samples work themselves out statistically would probably pick Obama as the leader, based on this group of polls, while pollsters who believe that samples are more accurate when they are small and customized to mirror the electorate would most likely favor Romney as the current frontrunner. Either way, as poll results vary widely, assumptions about the upcoming election will likely continue to change in the run up to the polls.
RealClearPolitics. General Election Romney Vs. Obama. Accessed May 15, 2012.