Controls Selection in Research Studies

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What is a common method used to investigate the association between diet and colorectal cancer?

Selecting patients with any condition and comparing their diets.
Selecting patients with colorectal cancer and a control group without the disease. (correct)
Choosing only patients with new cases of colorectal cancer.
Choosing patients randomly from various clinical services.

Why are incident cases preferred in research studies?

They have been diagnosed for a longer time period.
They are more likely to have a protective effect against cancer.
They are easier to recruit.
They are more representative of all cases in a population group. (correct)

How should cases be identified in a research study according to the protocol?

Through patient support groups.
By choosing prevalent cases only.
By recruiting anyone with any health condition.
From a primary care practice. (correct)

Why is it important for cases to be representative in a study?

To ensure accurate results for the defined population group. (A) Signup and view all the answers

What are some potential disadvantages of identifying cases through patient support groups?

Difficult to reach patients who might not be members of such groups. (D) Signup and view all the answers

In research studies, why might some studies focus on only part of the spectrum of a disease?

To better understand specific aspects of the disease. (C) Signup and view all the answers

What should normally be used in a case–control study for data analysis?

Odds Ratio (C) Signup and view all the answers

What should be taken into account when interpreting results of a case-control study?

Criteria for causality (D) Signup and view all the answers

Why is data in case-control studies prone to biases?

Data are retrospective (D) Signup and view all the answers

What is an advantage of using case-control studies over cohort studies?

Suitable for rare diseases (B) Signup and view all the answers

In case-control studies, what is calculated using the formula OR = (a/c) / (b/d)?

Odds Ratio (B) Signup and view all the answers

Which test can be employed for data analysis in case-control studies, besides the odds ratio?

Chi-squared test (C) Signup and view all the answers

What is the main aim of a case-control study?

To compare historical exposure to risk factors between diseased and non-diseased individuals (B) Signup and view all the answers

How do case-control studies differ from cohort studies?

Case-control studies are retrospective while cohort studies are prospective (D) Signup and view all the answers

What is the role of controls in a case-control study?

Controls provide a basis for comparison with the cases (C) Signup and view all the answers

Why are case-control studies considered easier and quicker to complete compared to cohort studies?

Cohort studies require follow-up over a long period of time (A) Signup and view all the answers

In a case-control study investigating a protective effect, what would be the expected outcome regarding exposure to the risk factor?

Cases would have lower exposure to the risk factor than controls (C) Signup and view all the answers

What is the most important principle when selecting controls for a study?

Randomly selecting controls from the population (C) Signup and view all the answers

Which type of study design is more prone to biases according to the text?

Retrospective case-control studies (D) Signup and view all the answers

Why is recalling biases a particular problem in case-control studies?

Cases are more likely to recall exposures than controls (B) Signup and view all the answers

How does having more controls per case affect a study?

It helps exclude chance as an explanation for any association (B) Signup and view all the answers

What is a suitable way to select controls for a study?

Randomly selecting controls from the same population as the cases (D) Signup and view all the answers

Why is it important for controls in a study to be representative of people without the disease?

To ensure that any associations are not confounded by disease presence (C) Signup and view all the answers

Interviews in a case-control study should be structured and ask the same questions of both cases and controls to avoid:

Recall bias (A) Signup and view all the answers