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How Much Day-to-Day Variation Should We Expect in the Gallup Poll?

Posted on August 28, 2008

Here's something that might help you to understand what Brad DeLong is talking about when he discusses the expected variation in the daily Gallup poll results (he follows up here). I'll just do one or two of the calculations to show how it's done, it's easy to take it from there.Let the poll result at time t be Pt. Brad has noted this has a standard deviation of 1.67 percent. Note this implies the variance of the daily poll is is var(Pt) = 2 = (1.67%)2 = (.0167)2 = .000277. 1. First, where does the 1.67 percent figure come from?To get this number, remember that the variance of P can be cal...

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