Getting to see opinion poll uncertainty
Rock’n Poll has a lovely guide to sampling uncertainty in election polls, guiding you step by step to see how approximate the results would be in the best of all possible worlds. Highly recommended.
Of course, we’re not in the best of all possible worlds, and in addition to pure sampling uncertainty we have ‘house effects’ due to different methodology between polling firms and ‘design effects’ due to the way the surveys compensate for non-response. And on top of that there are problems with the hypothetical question ‘if an election were held tomorrow’, and probably issues with people not wanting to be honest.
Even so, the basic sampling uncertainty gives a good guide to the error in opinion polls, and anything that makes it easier to understand is worth having.
(via Harkanwal Singh)
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »