Here's an update on Gallup’s thinking when we suspended our national daily tracking of the presidential election campaign as of Monday, Oct. 29. Basically, we reached the conclusion that Superstorm Sandy had compromised the ability of a national survey to provide a nationally representative assessment of the nation’s voting population.
An unprecedented estimated 8 million households have lost power because of the storm and many others have had their lives disrupted. Cell phone service has also been compromised in many areas. Additionally, those in the storm-affected regions who can be reached by phone may be unwilling or unable to be interviewed. Ascertaining likelihood to vote may also be problematic when many voters are uncertain of their access to the polls and may not be able to say with a high degree of confidence whether they will vote.
These problems are obviously not uniformly distributed across the country but are concentrated in parts of the Middle Atlantic and Northeast and in specific areas within these regions. Thus, while we could have achieved the targeted number of completed interviews in these regions, those interviews would not have been representative of the overall population of the area. New York state is a prime example. While it would be possible to complete the proportionate number of interviews in New York state, those interviews would be skewed disproportionately upstate, not in New York City and Long Island.
All survey data are weighted to match the demographic characteristics of the population as a whole, including weights for telephone use now that interviewing involves both land lines and cell phones. But it is impossible to adequately weight to compensate for large segments of the population who cannot be reached at all in a survey, or in very low percentages, and whose opinions may have changed from previous, pre-storm measures.
Gallup is now tentatively planning on conducting interviewing over the last four days of this week, Thursday through Sunday, to provide a final pre-election estimate of the election race. The decisions we make on the validity of the sample and the analysis of the data that results will be carefully informed by the degree of recovery from the storm over the period of the survey.