September 11, 2012

Surveys and political identity

A respectable survey in the US state of Ohio reports that Obama is still polling well. But it’s one of the secondary questions that is especially interesting: from Ezra Klein’s blog at the Washington Post

PPP asked voters who they thought deserved more credit for the killing of Osama bin Laden: Obama or Romney. 63 percent said Obama, 31 percent weren’t sure, and 6 percent said Romney.

The results for Republican voters were even more astonishing. 38 percent said Obama, 47 percent weren’t sure, and 15 percent said Romney. What the heck is going on?

As they go on to explain, this is an example of one of the big problems with opinion polls in situations where the respondents know what you are doing.  The tendency is for people to answer in the way that represents their political affiliations rather than their actual opinions.

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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 »