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pre-test probability

— For screening and diagnostic tests, the likelihood that someone has the target condition for which the test is being used



Full explanation:

The pre-test probability of a target condition is the prevalence of the target condition in the population to which the person being tested, by a screening or diagnostic test, belongs.

Signs, symptoms, other characteristics and the results of other diagnostic tests can be used to define different populations with different pre-test probabilities.


For example, the pre-test probability of breast cancer in a group of women who have been referred for breast biopsy is estimated to be 20%. This means that a woman who has a biopsy because of a suspicious breast lump has a 20% chance that the breast lump will be cancerous before the test is performed.

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