Sampling bias example via NASA, Pew Research Center, and Twitter

Today's post is one, small, to-the-point example of sampling bias.

On May 27, 2020, my family and I were awaiting lift-off for the (subsequently grounded) NASA/SpaceX launch. To no one's surprise, I was following NASA on Twitter during the hoopla, and I noticed this Tweet:

https://twitter.com/NASA/status/1265724481009594369

And I couldn't help but think: That is some sampling bias. Admittedly, their sample size is very impressive, with over 54K votes. But this poll went out to a bunch of people who love NASA so much that they follow it on Twitter.

What is a less biased response to this question? As always, Pew Research Center had my back. 58% of Americans responded that they definitely/probably weren't interested in traveling into space:

https://www.pewresearch.org/fact-tank/2018/06/07/space-tourism-majority-of-americans-say-they-wouldnt-be-interested/

If you want to expand upon this example in class, you could ask your students to Google around for information on the typical Twitter user and whether or not they are representative of the average American. You could also go to the link for the survey and learn more about the exact methodology used by Pew research to gather their data.

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