I came across this graphic being shared on facebook. When I saw the total respondents number my first thought was that based on my recollection, that's pretty much a typical number for national polls I've seen in the past.
So I decided to do a little bit of research and found that for a population of 150,000,000 (estimate of actual voters):
- A sample size of 385 will give you a confidence interval of +/-5% 19 times out of 20 (95%)
I'm going to presume this particular poll wasn't just to identify "Total Republican primary voters", but probably to survey Repubs, Dems and independents, in which case you can't really expect more than the 1289 total respondents. The weighted number of 355 isn't out of line with most polls where there is a +/- 5% margin of error.
I know the focus of the graphic is how the weighted number was arrived at. But if the Trump campaign is going to dismiss one poll for weighting, they shouldn't tout any poll at all. So who is really doing the misleading here?
Source: http://www.raosoft.com/samplesize.html
So I decided to do a little bit of research and found that for a population of 150,000,000 (estimate of actual voters):
- A sample size of 385 will give you a confidence interval of +/-5% 19 times out of 20 (95%)
I'm going to presume this particular poll wasn't just to identify "Total Republican primary voters", but probably to survey Repubs, Dems and independents, in which case you can't really expect more than the 1289 total respondents. The weighted number of 355 isn't out of line with most polls where there is a +/- 5% margin of error.
I know the focus of the graphic is how the weighted number was arrived at. But if the Trump campaign is going to dismiss one poll for weighting, they shouldn't tout any poll at all. So who is really doing the misleading here?
Source: http://www.raosoft.com/samplesize.html
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