Informative, not infallible: why polling mostly works pretty well (even though only about a thousand people usually get sampled)

Over the last few months, I’ve often heard that polls can’t be trusted. In particular, I have heard that they can’t be trusted because each one usually involves study of only about a thousand individuals. I have even heard that argument from a retired quantitative linguist.1 So I’ve put together this essay in order to explain how polls work, why a random sample of a thousand should usually be considered sufficient, and why the results should be treated as informative even though they do not enable us to predict precise numbers of votes (which is a particular problem when the results are going to be close — because then, precise numbers can make all the difference).

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