Diagnostic tests of medical conditions can have several types of results. The test result can be positive or negative, whether or not a patient has the condition. A positive test (+) indicates that the patient has the condition. A negative test (−) indicates that 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. (Enter your answers as fractions.) Test Result Test Result Column Total Condition Present 105 24 129 Condition Absent 25 46 71
(a) P(+ condition present): this is known as the sensitivity of a test.
(b) P(- | condition present); this is known as the false-negative rate.
(c) Pcondition absent); this is known as the specificity of a test.
(d) P(+ | condition absent); this is known as the false-positive rate
(e) Prcondition present and +); this is the predictive value of the test
(f) P(condition present and-)