Understanding observational versus experimental evidence requires separating what is known about vaping from assumptions that are often made about these products. Researchers study vaping in the United States through national surveys, longitudinal studies, laboratory research, toxicological assessments, and population-level surveillance. Two important federal data sources are the National Youth Tobacco Survey and the National Health Interview Survey. These surveys measure different populations and use different definitions, so their percentages should not be compared without understanding the methodology. Researchers also distinguish ever use from current use, frequency of use, and use of multiple tobacco products. Careful interpretation matters because a change in prevalence can reflect changes in behavior, product availability, survey methods, or population characteristics. A careful discussion should distinguish federal rules from state and local requirements and should distinguish established findings from questions that remain under study.
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