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If we want to know something about a large group of people, we can take a sample and give them a survey. This tutorial introduces how that process works.

“A new study shows that people who eat lobster regularly tend to live longer.” That may be true, but it doesn’t necessarily mean that eating lobster causes people to live longer. We could set up an experiment to find out if lobster is truly the cause. This tutorial covers the difference between observational studies and experiments.
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