Removal of Healthy Appendixes

Computed tomography (CT) scans are used to diagnose the need for the removal of the appendix. CT scans give the patient a large level of radiation, which has risks, especially for young people.

There is a new form of CT scanning called low-dose CT, which was tested to see whether it was inferior when diagnosing appendicitis. Negative appendectomies are appendectomies that were done even though the appendix was healthy.

The negative appendectomy rate was 6 of 172 patients randomly assigned to the low-dose CT and 6 out of 186 patients randomly assigned to the standard-dose group.

a. Find the negative appendectomy rates for both samples and compare them.

b. Test the hypothesis that the negative appendectomy rate and dosage are independent at the 0.05 level.