Researchers periodically survey a few thousand of the patients taking a certain medication in order to make connections between that medication and the subjects’ general health. This method of gathering data is classified as

The researchers collect information by asking or surveying a few thousand patients, which is only part of the full group of patients taking the medication. Gathering data from a subset this way is a sample survey. It is not an experiment because the researchers are not assigning treatments or changing what the patients take.

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