Online opt-in polls can produce misleading results, especially for young people and Hispanic adults
We examine how an opt-in poll may have unintentionally misled the public about the sensitive issue of Holocaust denial among young Americans.
Andrew Mercer is a principal methodologist at Pew Research Center. He is an expert on probability-based online panels, nonprobability survey methods, survey nonresponse and statistical analysis. His research focuses on methods of identifying and correcting bias in survey samples. He leads the Center’s research on nonprobability samples and co-authored several reports and publications on the subject. He also served on the American Association for Public Opinion Research’s task force on Data Quality Metrics for Online Samples. He has authored blog posts and analyses making methodological concepts such as margin of error and oversampling accessible to a general audience. Prior to joining the Center, Mercer was a senior survey methodologist at Westat. He received a bachelor’s degree in political science from Carleton College and master’s and doctoral degrees in survey methodology from the University of Maryland. His research has been published in Public Opinion Quarterly and the Journal of Survey Statistics and Methodology.
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Comparing Two Types of Online Survey Samples
Pew Research Center conducted a study to compare the accuracy of six online surveys of U.S. adults – three from probability-based panels and three from opt-in sources. On average, the absolute error on opt-in samples was about twice that of probability-based panels.
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Does public opinion polling about issues still work?
National polls like the Center’s come within a few percentage points, on average, of benchmarks from high response rate federal surveys.
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Assessing the Risks to Online Polls From Bogus Respondents
While the growth of online interviewing is a prominent trend in polling, there is variation within that trend in how researchers recruit respondents. This study finds that sourcing affects data quality.
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A closer look at police officers who have fired their weapon on duty
About a quarter of all officers say they have ever fired their service weapon while on the job. Are some more likely than others to have fired their weapon in the line of duty?
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Behind the Badge
Majorities of police officers say that recent high-profile encounters between black citizens and police have made their jobs riskier and left many officers reluctant to fully carry out some of their duties.
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Why 2016 election polls missed their mark
There is a great deal of speculation but no clear answers as to the cause of the disconnect, but there is one point of agreement: Across the board, polls underestimated Trump’s level of support.
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Oversampling is used to study small groups, not bias poll results
As oversampling and its possible effect on presidential polls are spotlighted ahead of Election Day, learn more about this practice and how pollsters adjust for it.
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5 key things to know about the margin of error in election polls
Some of the better-known statistical rules of thumb that a smart consumer might think apply in polls are more nuanced than they seem. In other words, as is so often the case in life, it’s complicated.
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