Case-control

Question 1

give the formula for the odds ratio

Answer 1

OR = (axd) / (bxc)

Question 2

how can precision of the odds ratio be improved

Answer 2

by increasing the number of controls

Question 3

Give the two types of bias that case control is prone to

Answer 3

selection and recall

Question 4

give some characteristics of case control studies

Answer 4

good for rare diseases but not rare exposures
can look at many differnet exposures
cheap and quick
cannot give absolute incidence rates and cannot be compared to the general population
may be difficult to be sure the exposure proceeded the disease

biases - selection and recall

Question 5

what is the key difference between cohort and case-control studies?

Answer 5

a cohort study identifies people on basis of exposure and compares disease outcomes

a case-control identifies people on basis of disease and looks back and compares on exposure status