Why Gallup only poll showing Romney with seven-point lead over Obama nationally

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Washington, Oct. 19: The already controversial Gallup Daily Poll has raised even more eyebrows after it released a poll showing Republican presidential nominee Mitt Romney leading over President Barack Obama by 7 percentage points among likely voters nationally.

The latest Gallup Poll result was by far the most favorable to Romney among national polls released over the past week.

Its results are highly inconsistent with the results that other polling firms are showing in the presidential race, and the Gallup poll has a history of performing very poorly.

Other national polls show a race that is roughly tied on average, while state polls continue to indicate a narrow advantage of about two points for Obama in tipping-point states like Ohio, the New York Daily News reports.

Over the past 10 days since Gallup started reporting its tracking results among likely voters, the results have typically shown a reasonably constant gap-roughly 5 percentage points-between the likely and registered voter samples, the report said.

The Gallup poll was taken over seven days, through Wednesday, and thus only included one day of data since the second presidential debate, at Hostra University on Long Island.

There are two major pieces of information that is extracted from each poll. One is simply the raw number – who is ahead or behind? The other is the trend it shows in the race – which candidate is gaining or losing ground?

Because national tracking polls like Gallup are published every day, they are useful for the trend part of the calculation, measuring the change in the race against a constant baseline, it added.

Of all the daily tracking polls, the Gallup survey uses a larger sample size, and it has a methodology that includes calls to cell phone voters.

On the other hand, the pollster ratings are also based in part on past accuracy, and Gallup’s performance is middling in that department.

According to the report, it mostly gets a lot of weight by comparison, since the tracking surveys are a mediocre group on the whole.

The relative amount of weight assigned to each type of poll is fluid rather than fixed, and depends on the overall volume of data. On days when a large number of state polls are published, but few national ones, they will generally be the more useful source for making inferences about the trend in the race.

But on average since Oct. 1, the Gallup national tracking poll has accounted for 12 percent of the information that the model uses to calculate the trend line, the report added. (ANI)