June 2018

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The May 2018 VOTER Survey (Views of the Electorate Research Survey) was conducted in partnership with the survey firm YouGov. In total, 6,005 adults (ages 18 and up) with internet access took the survey online between April 5 and May 14, 2018.

Of these respondents, 4,705 individuals were originally interviewed by YouGov in 2011–2012 as part of the 2012 Cooperative Campaign Analysis Project (CCAP), and then again in the December 2016 VOTER Survey. In addition, 4,052 of these 4,705 respondents were also interviewed in the July 2017 VOTER Survey. Thus, most respondents had previously participated in five prior surveys: December 2011, November 2012, July 2016 (presidential primary vote preference), December 2016, and June 2017.

The May 2018 VOTER Survey also included interviews with 500 Hispanic respondents and 800 respondents ages 18 to 24. These respondents had not previously been included in the 2012 CCAP or the earlier VOTER Surveys. In particular, the sub-sample of 18 to 24-year-olds would not have been eligible for the CCAP, given their age in 2012.

The 2012 CCAP was constructed using YouGov’s sample matching procedure. A stratified sample is drawn from YouGov’s panel, which consists of people who have agreed to take occasional surveys. The strata are defined by the combination of age, gender, race, and education, and each stratum is sampled in proportion to its size in the U.S. population. Then, each element of this sample is matched to a synthetic sampling frame constructed from the U.S. Census Bureau’s American Community Survey, the Current Population Survey Voting and Registration Supplement, and other databases. The matching procedure finds the observation in the sample from YouGov’s panel that most closely matches each observation in the synthetic sampling frame on a set of demographic characteristics. The resulting sample is then weighted by a set of demographic and non-demographic variables.

On average, YouGov’s methodology produces less bias across a series of benchmarks than do other methodologies using online samples. For more information see:

  • Stephen Ansolabehere and Douglas Rivers, “Cooperative Survey Research,” Annual Review of Political Science, Vol. 16, pp. 307-329, May 2013.
  • Courtney Kennedy, et al., “Evaluating Online Nonprobability Surveys,” Pew Research Center, May 2, 2016. (Available here).
  • Doug Rivers, “Pew Research: YouGov consistently outperforms competitors on accuracy,” YouGov, May 13, 2016. (Available here).

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