Diagnostic tests of medical conditions can have several types of results. The te
ID: 3043366 • Letter: D
Question
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 a condition are shown. Condition Absent 20 45 65 Assume the sample is representative of the entire population. For a person selected at random, compute the following probabilities Test Result + Test Result - Column Total Condition Present 110 25 135 Row Total 130 70 200 (Enter your answers as fractions.) (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) P(- | condition absent); this is known as the specificity of a test (d) P(+ 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 -)Explanation / Answer
a)P(+|condition persent) =110/135 =22/27
b) P(-|condition present) =25/135 =5/27
c) P(-|condition absent) =45/65 =9/13
d)P(+|condition absent)=20/65=4/13
e) P(condition present and +) =110/200=11/20
f) P(condition present and -) =25/200=1/8
(please revert for any clarification)