Nikki Haley: Now you see it, now you don't. Photo source: Getty Images
Why, in the words of the Politico title, does
Nikki Haley poll better against Joe Biden than Donald Trump does? One reason: Reporters
bungle the poll results.
Nowhere in this article does Steven Shepard even
mention a margin of error – that is, the absolute value in which the reported difference
between two candidates may well mislead us. For example, suppose that the
margin of error is 2% but the pollsters report that in their tabulation, DeSantis
leads Biden by 1%. This statement means nothing. We don’t know whether DeSantis
leads Biden, or Biden leads DeSantis, in even the polled sample itself. Errors
occur in hearing, writing down, and tabulating a respondent’s response. It would not be unusual for such errors to
affect 1% of the reported responses. In addition to that, the sample is almost
never a 100% accurate mirror of the population that interests us—for example, of
likely primary voters. Pollsters normally do not distinguish between the error that
occurs in reporting the sample and the error that occurs in projecting the
sample to the population. They just report one margin of error. So it would be
best if reporters stuck to results falling outside of the margin of error. For example, the article reports that in the Fox
News poll, Trump leads Biden among men by 13 percentage points. No respectable poll can have a margin of
error as large as 13%. So the reader can safely infer that Trump leads Biden
among men.
The article mentions 36 statistical comparisons or potential comparisons of poll results. Eight of them, or 22% of them all, imply a margin of 4% or less. This is within a common margin
of error in national political polls. In other words, more than a fifth of the
results reported by Shepard may well be flat wrong. Somebody should take away
this guy’s fishing license until he learns how to fish. – Leon Taylor, Baltimore tayloralmaty@gmail.com
Notes
For helpful comments, I thank but do not implicate
Paul Higgins, Mark Kennet, and David Schatz.
Reference
Steven Shepard. Why Nikki Haley polls better against Biden than Trump - POLITICO . December 9, 2023.
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