Case-control Studies Flashcards
How do you calculate an odds ratio?
(Diseased+exposed X Non-diseased+ unexposed) /
Non-diseased+exposed X Diseased+unexposed
Why is it advantageous to increase the number of controls in a case control study?
More controls, lowers the error factor
What is a nested case-control study?
The collection of data from the evolving outcome and exposure database of a concurrent or prospective cohort study
What are the advantages of using a nested case control study over a conventional case control study?
- Incidence rates can be calculated
- Population for sampling of controls is already defined
What are the advantages of using a nested case control study over a conventional cohort study?
It can collect more detailed information for a minority of participants
What are the two type of bias that case control studies are subject to?
Selection bias Information bias (recall bias and assessor bias)
What is non-differentiated misclassification and what it’s affect on the odds ratio?
Non differentiated misclassification is factors like randomly inaccurate measurements. It will cause the odds ratio to shrink to the null.
What is systematic misclassification and what it’s affect on the odds ratio?
Systematic misclassification is things like recall and assessor bias. This causes the odds ratio to move away from the null value.
Which is cheaper and quicker? Case-control or cohort studies?
Case-control studies
What is the difference between an odds ratio and an incidence rate ratio?
An odds ratio is affected by the number of controls as well as the number of cases
Which types of study is prone to losses to follow-up? Cohort studies or case-control studies?
Cohort studies
What is the rare disease assumption?
It assumes if the prevalence is low then the odds ratio is similar to the relative risk
