Glossary Term

# Predictive Values

Predictive values in diagnostic testing, are the proportion of true positives and true negatives. The positive predictive value (PPV) and negative predictive value (NPV) describe the accuracy of a diagnostic test; however, unlike sensitivity and specificity, predictive values are largely dependent on the prevalence of the dysfunction in the examined population.

**Predictive values:** in diagnostic testing, are the proportion of true positives and true negatives. The positive predictive value (PPV) and negative predictive value (NPV) describe the accuracy of a diagnostic test; however, unlike sensitivity and specificity, predictive values are largely dependent on the dysfunctions prevalence in the examined population (1). For example, imagine a patient who just tested positive on a special test. If the test was positive, what is the probability that they really have that dysfunction; how worried should they be? Now, imagine the same test performed on a very different individual in a different setting with very different subjective indicators. How do you think that would effect the predictive value?

**Positive predictive value (PPV)**- describes the probability of having a dysfunction of interest in a subject with a positive result. Therefore PPV represents the proportion of patients with positive test results that are positive in a given population.**Negative predictive value (NPV)**- describes the probability of not having the dysfunction of interest in a subject with a negative test result. Therefore NPV represents the proportion of patients without the disease that are negative in a given population.

- Šimundić, A. M. (2009). Measures of diagnostic accuracy: basic definitions.
*Ejifcc*,*19*(4), 203

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## Synonyms

- Positive predictive value
- Negative predictive value
- PPV
- NPV