Correcting Polling Error in Over-Engaged Samples Using Representative Turnout Weighting

11 Pages Posted: 24 Jan 2016

See all articles by Jonathan Mellon

Jonathan Mellon

University of Manchester

Christopher Prosser

University of Manchester

Date Written: January 22, 2016

Abstract

In previous research (Mellon & Prosser, Missing Non-Voters and Misweighted Samples: Explaining the 2015 Great British Polling Miss) we show that the primary cause of the polling miss at the 2015 UK General Election was the undersampling of less politically engaged respondents, particularly non-voters. We show that this problem can partially be corrected after the fact by including turnout as a weighting factor. In this paper we elaborate and extend this method and show that it could be applied prior to an election as well. We do so by estimating the probability of respondents will vote in the election and calibrate the distribution of turnout probabilities so that the expected level of turnout in the sample matches is pegged to that expected in the election. Using data that was available prior to the 2015 election we demonstrate that had this method been applied to the BES Internet Panel survey it would have substantially reduced the level of error in the survey.

Keywords: polling miss; british election 2015; representative samples; survey weighting; online polling; survey methodology; political polling; public opinion

Suggested Citation

Mellon, Jonathan and Prosser, Christopher, Correcting Polling Error in Over-Engaged Samples Using Representative Turnout Weighting (January 22, 2016). Available at SSRN: https://ssrn.com/abstract=2720206 or http://dx.doi.org/10.2139/ssrn.2720206

Jonathan Mellon

University of Manchester ( email )

Oxford Road
Manchester, M13 9PL
United Kingdom

Christopher Prosser (Contact Author)

University of Manchester ( email )

Oxford Road
Manchester, M13 9PL
United Kingdom

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