Calculating sensitivity
A screening test is positive in 150 of 200 patients who have the disease. What is its sensitivity?
Answer A: explanation for every choice
A
Correct. Sensitivity = TP/(TP + FN) = 150/200 = 75%.
B
25% is the false negative rate (50/200).
C
This inverts the ratio. Sensitivity can't exceed 100%.
D
Healthy patients are needed for specificity, not sensitivity.
TakeawaySensitivity uses only people with the disease. Specificity uses only people without it.
Equation usedSensitivity, specificity, and predictive values
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