Probability using contingency table.
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 tests (+) indicates the patient has the condition. A negative test (-) indicates patient does not have the condition. Remember, the positive test does not prove the patient has the condition. Extra medical work may be required. Consider the 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.
Suppose 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 the 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 the test.
d. P (+, given condition absent); this is known as the sensitivity of the test.
e. P (+, given condition present); this is known as the false-negative rate.
f. P (condition present and -)