specificity – when referring to the accuracy of a test result, specificity refers to the proportion of people who do not have an illness or disease who have a negative test result.
If a test has low specificity, the concern is over false-positive results – where people who to not have a condition are wrongly diagnosed as having it.
If a test has high specificity, then people who to not have a condition are correctly ruled out from the condition.
For a serious condition, high specificity is essential to prevent people being unnecessarily treated.
See sensitivity.