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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.

 

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Pretest Probability

Definition: The probability that a person has a particular disease before any test results are obtained. The pretest probability for large groups of people (such as the population of a city) is the same as the prevalence of the disease in that group.

Example: For example, breast biopsy is a highly accurate test for finding out whether a breast lump is breast cancer. The pretest probability of breast cancer in a group of women who have been referred for breast biopsy is estimated to be 20 percent. This means that a person who has a biopsy because of a suspicious breast lump has a 20 percent chance that the breast lump will be cancerous even before the test is performed.

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