Question

1.      A diagnostic test has a probability 0.95 of giving a positive result when applied to a person suffering from a certain disease, and a probability 0.10 of giving a (false) positive when applied to a non-sufferer. It is estimated that 0.5 % of the population are sufferers. Suppose that the test is now administered to a person about whom we have no relevant information relating to the disease (apart from the fact that he/she comes from this population). Calculate the following probabilities:
a)      that the test result will be positive;
 
 
 
 
b)     that, given a positive result, the person is a sufferer;
 
 
 
 
c)      that, given a negative result, the person is a non-sufferer;
 
 
 
 
 
d)     that the person will be misclassified (misdiagnosed).
 
 

Answer 1