Mr.Patient tested positive for disease X.He went to see Dr.Gordis and asked him what was the probability of truly being sick given the results of the test.To answer that question,Dr.Gordis must know what about the test?

A) Sensitivity
B) Specificity
C) Prevalence
D) Positive predictive value
E) Negative predictive value

The positive predictive value precisely represents the probability of having a disease given that the result from a test was positive.Sensitivity and specificity are the abilities of a test to recognize people with and without the disease,respectively.However,they do not provide information regarding the probability of having a disease given the result of the test.Negative predictive value represents the probability of not having a disease when the result of the test is negative.