- Try the following parameters:
base rate: .80
true positive: .50
false positive: .50
Compare P(D|T) to P(D) to determine whether the test has any usefulness.
- Try the following parameters:
base rate: .01
true positive: .99
false positive: .05
Notice that even though the test is very accurate, most of the people diagnosed
testing positive do not have the disease.
- Suppose a test of suicidal behavior has a hit rate of .85 and a false
positive rate of 0.10. Further suppose that the rate of suicide attempts
in a college were 0.05. If the test were given to all students in the college
and those testing positive were hospitalized to prevent suicide, what proportion
of those hospitalized would have attempted suicide.
- Tryout various other combinations of the parameters and explore the results.