The nation’s most well-respected polling company, Gallup, under-estimates the public’s support for President Obama because it uses measures that don’t properly count the proportion of black and Hispanic voters who will come to the polls, according to an exhaustive analysis on the Huffington Post.
The media’s reporting on election campaigns has become to a large extent a daily recitation of results from the major polling sources, such as Gallup, CNN, ABC, the New York Times and NBC. Because Gallup takes daily tracking polls and has been doing it for so long, the Gallup poll is considered the most influential in the country. But a story by Mark Blumenthal on the Huffington Post says the Gallup poll is deceptive because it consistently shows the election to be closer than the other polling sources. Blumenthal writes that this is because of several differences in the way that Gallup collects its information and weights the numbers to account for the population’s racial breakdown.
Every poll must count the number of people in each racial group that participated in the poll and attempt to extrapolate to determine how well the sample represents the country and the people who will vote. In deciding how many black and Hispanic households should be used when it weights its numbers according to the population, Gallup uses the number of households that have home or mobile phones. This means that households with no phone would not be counted by Gallup—so the percentage of blacks and Hispanics in the voting population will be undercounted by Gallup.
Gallup also allows people to pick membership in more than once racial group, which could reduce the number of people who call themselves black—thus also reducing the number of blacks that Gallup counts in the voting population.
There are several other ways that Gallup undercounts the black population, according to Blumenthal.
Because Obama enjoys such widespread support in the black community, any moves that lower the percentage of blacks in their sample can significantly lower the level of support for the president in the poll results.