Question: Survey: Medical Tests

Diagnostic tests of medical conditions have several results. The test result can be positive or negative, whether or not a patient has the condition. A positive (+) test indicates the patient has the condition. A negative test (-) indicates the patient does not have the condition. Remember, a positive test does not prove the patient has the condition. Additional medical work may be required. Consider a random sample of 200 patients, some of whom have a medical condition and some of whom do not. Results of a new diagnostic test for the condition are shown.

Assume the sample is representative of the entire population. For a person selected at random, compute the following probabilities:

a.) P (+, given condition present); this is known as the sensitivity of a test

b.) P (- , given condition present); this is known as the false-negative rate

c.) P (- , given condition absent); this is known as the specificity of a test.

d.) P (+, given condition absent); this is known as the false-positive rate.

e.) P (condition present and +); this is the predictive value of the test.

f.) P (condition present and -).