A particular diagnostic test for disease X has a sensitivity of 90% and a specificity of 90%. What is the negative predictive value of the test?

Question

kropot72 · Answer

The information at this link will enable you to solve the question: https://en.wikipedia.org/wiki/Sensitivity_and_specificity

anonymous · Answer

I've looked through calculations of negative predictive value, and I believe there's not enough information to find it given only the sensitivity and specificity?

anonymous · Answer

There are four cases:
(test, actual)

(neg, neg) - 90%
(neg, pos)
(pos, neg)
(pos, pos) - 90%

anonymous · Answer

You are missing (neg, pos), but you may be able to deduce it by using various properties of probability.

anonymous · Answer

(pos, pos) + (neg, pos) = 100%
In this case:
90% + (neg, pos) = 100%

Then we have what we need:
NPV = (neg, neg) / [ (neg, neg)  + (neg, pos)  ]

anonymous · Answer

Ans: 90%...Is that correct?