Question

Treating prostate disease A large study used records from Canada’s national health care system to compare the effectiveness of two ways to treat prostate disease. The two treatments are traditional surgery and a new method that does not require surgery. The records described many patients whose doctors had chosen what method to use. The study found that patients treated by the new method were more likely to die within$8$years.

a. Further study of the data showed that this conclusion was wrong. The extra deaths among patients who were treated with the new method could be explained by other variables. What other variables might be confounded with a doctor’s choice of surgical or nonsurgical treatment?

b. You have$300$prostate patients who are willing to serve as subjects in an experiment to compare the two methods. Write a few sentences describing a completely randomized design for this experiment.

Short answer

(a) The other variables controlling the treatments are the patients' conditions and also the money they have.

(b) The patients can be divided in various ways to choose between both treatments, like half can undergo surgical methods and the other half can go with non-surgical methods.

Step-by-step solution

Part (a) Step 1: Given Information

We are given an experiment where doctors are using two methods to treat patients, surgical and non-surgical, and we have to find out other variables which can affect the methods.

Part (a) Step 2: Explanation

According to the question, doctors have to advise patients about the treatments they can undergo that are surgical or non-surgical. But besides treatments, there are other variables which can affect the treatments, like the condition of the patient and the amount of money they have.

Part (b) Step 1: Given Information

We are given an experiment where doctors are using two methods to treat patients, surgical and non-surgical, and we have to find out how three hundred patients can be randomized.

Part (b) Step 2: Explanation

According to the question, three hundred patients are available, and the patients should be randomized in such a way that fifty students should undergo surgical methods and the other one hundred fifty should undergo non-surgical methods. Another one can be in such a way that one hundred forty students can undergo surgical methods and one sixty students can undergo non-surgical methods and there are many other ways for randomization.