How to Use Statistics to Understand Poll Results

Learn how to use statistics to understand the significance of the latest political polling results and to keep yourself from being duped by misleading information.

Jason Marshall, PhD
5-minute read
Episode #28

How to Know if Political Poll Results are Significant Or Not

Now, let’s go back to our original question: Should you trust the results of a poll? Well, let’s return to our imaginary presidential poll in which candidate A received the support of 42% of the population and candidate B received the support of 46% of the population, with a margin of error of ±3%. This means that candidate A could have up to 45% of the support and candidate B could have as little as 43% of the support, so that while the poll seems to indicate a 46% to 42% lead for candidate B, it cannot actually be used to determine who is really leading—no matter how many times pundits claim otherwise—since the margin of error is too big.

If, however, the margin of error were smaller—something like ±1.5% instead of ±3% could be achieved by polling a significantly larger sample of the population—then candidate B’s 4% lead would actually be significant since (with 95% confidence) candidate B would have a minimum of 44.5% of the vote to the maximum 43.5% support of candidate A. The general rule of thumb is that the lead must be at least twice the margin of error to be significant, and the quick and dirty tip is therefore to be sure and pay attention to margins of error—without them, poll results are essentially meaningless.

Wrap Up

That’s all the math we have time for today. And that’s all the time we’re going to take to talk about statistics too—for now, at least. In upcoming episodes, we’ll be heading back to math basic training to talk some more about math fundamentals.

Please email your math questions and comments to mathdude@quickanddirtytips.com. You can get updates about the Math Dude podcast, the “Video Extra!” episodes on YouTube, and all my other musings about math, science, and life in general by following me on Twitter. And don’t forget to join our great community of social networking math fans by becoming a fan of the Math Dude on Facebook.

Until next time, this is Jason Marshall with The Math Dude’s Quick and Dirty Tips to Make Math Easier. Thanks for reading, math fans!

Poll image from Shutterstock


About the Author

Jason Marshall, PhD

Jason Marshall is the author of The Math Dude's Quick and Dirty Guide to Algebra. He provides clear explanations of math terms and principles, and his simple tricks for solving basic algebra problems will have even the most math-phobic person looking forward to working out whatever math problem comes their way.

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