How to tell if a political poll is credible

This is part of “Can You Believe It?” a series of stories and resources focused on giving you the tools to fight disinformation heading into Election 2020. You can find more resources here. What have you been seeing? Share here.

What they are

Political polls attempt to gauge public opinion on certain issues and/or candidates running for election. They can help give voters and those working on campaigns a sense of what is important to the general public as well as specific demographics. They can also signal how well a candidate is connecting to voters. The content and sample sizes can vary widely, but it’s one way voters can express their thoughts on a large scale and let candidates know what they want.

Who makes them

Political polls are often run or funded by campaigns, research firms or media companies. But anyone with access to a survey tool can host one on the internet and present their findings.

Why they can be dangerous

Major media outlets and many survey research firms looking to preserve their credibility have a strong incentive for investing in solid surveys. Still, some pollsters and media outlets have other motives, like promoting a particular candidate or idea.

A survey’s line of questioning and results can be manipulated to present a trend that isn’t really there, prompt an audience to only answer a certain way or only address the thoughts and needs of a specific demographic.

How to determine a poll’s credibility

Before you put too much stock into the results of a poll, especially one you find online, ask these questions:

Who funded it? Advocacy groups and those affiliated with campaigns obviously have a stake in the outcome, so news organizations often ignore their poll results, or write about them only after giving them a high level of scrutiny.
What is the target population? Political polls can focus on the voting-age population, likely voters, or registered voters. All can be valid but can yield different results.
What are the sampling methods? Polls that rely only on landlines are no longer valid. Similarly, internet-based polls that rely exclusively on people choosing to opt in aren’t reliable.
Are the results weighted? It’s impossible to get a sample that perfectly reflects the target population, no matter how good the sampling methods. So mathematical adjustments are made after-the-fact to make the poll as accurate as possible. For example, if 18-to-34-year-olds only make up 5 percent of respondents but make up 20 percent of the population, adjustments are made to account for that.
What does the poll ask? A credible survey will usually provide access to the original questions and at least the basic “topline” results.

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