Cohort Study, you are studying
the risk factorand see if you can associate a disease to it.
Therefore, you use Relative Risk and Attributable Risk. You can measure
incidence in prospective and retrospective cohort studies. Note that cohort study can be
retrospective i.e you follow the cohort in past time by checking their
hospital records. For example, you can say the incidence of pulmonary
tuberculosis was xx% in Asian immigrants who immigrated to the US in the period
you are studying the disease and see if you can associate risk factorsto it. Therefore, you use Odds Ratio. Case-Control Studies are
typically done for rare diseases; you compare the small number of rare disease
with a control group and find out if there was a risk factor that might have
caused their disease. Commonly case control studies are retrospective.
For Example: If you make a study to find out the
percentage of smokers among lung cancer patients versus the percentage of
smokers among those who do not have lung cancer then this is case-control.
Conversely, if you follow smokers and non-smokers in time and see who develop
lung cancer or not, then this is a cohort study. Please see attached more info.
Hope this helps.