Consider a screening test for Rocky Mountain Fever that has reasonably good
specificity and sensitivity: Of people who have the illness, 95% get a positive
result on the test, and of people who don’t have the illness, 92% get a negative
result on the test. Now consider Rockytown, which has a population of 10,000
people; in the town, 100 people have Rocky Mountain Fever.
a. Fill out a table or draw a tree diagram to show how the test would perform
if you used it to screen the residents of Rockytown.

Question

Consider a screening test for Rocky Mountain Fever that has reasonably good
specificity and sensitivity: Of people who have the illness, 95% get a positive
result on the test, and of people who don’t have the illness, 92% get a negative
result on the test. Now consider Rockytown, which has a population of 10,000
people; in the town, 100 people have Rocky Mountain Fever.
a. Fill out a table or draw a tree diagram to show how the test would perform
if you used it to screen the residents of Rockytown.

anonymous · Answer

b. Compute the positive predictive value (probability of having the disease
given the test is positive).
c. Compute the negative predictive value (probability of not having the
disease given the test is negative).
d. Comment on these rates and what they mean for the usefulness of the test

owen3 · Answer

did you make a probability tree