Negative predictive value
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Negative predictive value of a test/investigation is defined as the proportion of patients with negative results being truly disease free.
Calculation
Negative predictive value = true negatives detected/total / total negative results
where, total(where "total negative results" = true negative + false negative)
Bayes' theorem
One can also determine the NPV with an estimate of sensitivity, specificity, and pretest probability (p).
NPV = [(specificity) x (1 - p)] / [specificity x (1 - p) + (1 - sensitivity) x (p)]
See alsoPractical points
- unlike sensitivity and specificity, NPV is highly dependent on the prevalence of the disease in the target population
specificitypositive predictive valuep value
-<p><strong>Negative predictive value </strong>of a test/investigation is defined as the proportion of patients with negative results being truly disease free.</p><h4>Calculation</h4><p>Negative predictive value = true negatives detected/total negative results</p><p>where, total negative results = true negative + false negative</p><h4>See also</h4><ul>-<li><a href="/articles/sensitivity">sensitivity</a></li>-<li><a href="/articles/specificity">specificity</a></li>-<li><a href="/articles/positive-predictive-value">positive predictive value</a></li>-<li><a title="p value" href="/articles/p-value">p value</a></li>-</ul>- +<p><strong>Negative predictive value </strong>of a test/investigation is defined as the proportion of patients with negative results being truly disease free.</p><h4>Calculation</h4><p>Negative predictive value = true negatives detected / total negative results</p><p>(where "total negative results" = true negative + false negative)</p><h6>Bayes' theorem</h6><p>One can also determine the NPV with an estimate of sensitivity, specificity, and pretest probability (p).</p><p>NPV = [(specificity) x (1 - p)] / [specificity x (1 - p) + (1 - sensitivity) x (p)]</p><h4>Practical points</h4><ul><li>unlike sensitivity and specificity, NPV is highly dependent on the prevalence of the disease in the target population</li></ul>
References changed:
- 2. Weinstein S, Obuchowski NA, Lieber ML. Clinical evaluation of diagnostic tests. AJR Am J Roentgenol. 2005;184 (1): 14-9. <a href="http://dx.doi.org/10.2214/ajr.184.1.01840014">doi:10.2214/ajr.184.1.01840014</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/15615943">Pubmed citation</a><span class="auto"></span>
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- statistics
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