Negative Predictive Value Calculator | NPV Calculator

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True negatives (TN)

True Negatives (TN) = patients who do NOT have the disease AND the test is correctly negative. In SPSS Crosstabs: Disease=No row, Test=Negative column. Example: 80 healthy patients correctly tested negative.

False negatives (FN)

False Negatives (FN) = patients who have the disease BUT the test missed them (negative result). In SPSS Crosstabs: Disease=Yes row, Test=Negative column. Example: 5 diseased patients incorrectly tested negative. NPV = TN ÷ (TN + FN) = 80 ÷ 85 = 94.1%. NPV is high when disease is rare in the tested population.

Required Terms Explained

Negative predictive value = TN / (TN + FN). It answers: if the test is negative, what is the probability the patient truly does not have the disease?

TN: correct negative test result.

FN: missed disease case.

NPV depends on prevalence: NPV changes when disease prevalence changes, even if sensitivity and specificity stay the same.