In the paper regarding a baby of the author's colleague, the heel stick blood test for creatinine phosphokinase (CPK) was used as a diagnostic test for multiple schlerosis in infants.
The test had seemingly amazing characteristics. Suppose that the sensitivity of the test is 1.00, and the specificity of the test is 0.9998. We suppose that the prevalence of muscular distrophy among infants is 0.0002 (1 in 5000). Please give all answers to 4 decimal places.
a) What is the probability of a false positive test (the probability that a person not having muscular distrophy would test positive)? Please give your answer to 4 decimal places.
b) What is the probability of a false negative test (the probability that a person having muscular distrophy tests negative)?
c) What is the predictive value of a positive test result? I'm asking for P(disease|test+).
d) ) What is the predictive value of a negative test result? I'm asking for P(no disease|test-).