Question

Controls are needed in a case-control study because: A. They are matched to the cases for suspected etiologic factors B. They may be followed to determine if they develop the disease in question C. They increase sample size, so that statistical significance may be achieved D. They provide a comparable estimate of the frequency of exposure in the absence of disease E. They reduce bias

Answer 1

Answer:

D. They provide a comparable estimate of the frequency of exposure in the absence of disease                                    

Explanation:

Case-control study: The case-control study is also referred to as a case-referent study. This is one of the types of observational study that compares and identifies two different groups which differs in outcome based on a few casual attributes.

In the case-control study, two steps are involved:

1. To identify the cases. Here, the cases are known as a group that consists of the outcome.

2. The controls are a group which is known to be free from the outcome.

In the question above, controls are needed in a case-control study because they provide a comparable estimate of the frequency of exposure in the absence of disease.