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Glossary of Terms

We know that many of the concepts used on this site can be difficult to understand. For that reason, we have provided you with a glossary to help you make sense of the terms used in Comparative Effectiveness Research. Every word that is defined in this glossary should appear highlighted throughout the Web site. When you come upon a highlighted term and would like to read the full definition, you can either click on the word to visit the glossary or roll your mouse over the word for a pop-up definition.

 

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External Validity

Definition: The extent to which clinical research studies apply to broader populations. A research study has external validity if its results can be generalized to the larger population.

Example:

For example, researchers analyzed a group of studies to determine the effectiveness of diagnostic tests for breast cancer. In general, the prevalence of breast cancer for women who undergo these tests is 20 percent. The prevalence of breast cancer in most of the studies the researchers analyzed was 50 percent or higher. These high prevalences suggested that the women studied were not typical of the general population. Therefore the studies lacked external validity.

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