What is the comparison and difference between a case control study and a cohort study, the epidemiological studies mostly used in epidemiology?

Answer 1

A cohort study: study design that is best suited for rare exposures. Cohort studies can either be prospective or retrospective and involve following people over time to determine until they develop an outcome, are lost to follow up or the study ends. Cohort studies can be more expensive than case-control studies but are viewed more favorably on the pyramid of strength of evidence.

A case-control study: study design that is best suited for rare outcomes (events or diseases) or outcomes with long Iatency. A case-control study involves finding cases first and retrospectively recording information on their exposures. A case-control study can use different methods of sampling for the cases and controls. Prevalent or Survivor sampling samples the controls from the disease-free population after the cases have been sampled. Risk set or Density sampling samples the controls from the same population at risk when the cases occur. Case-base sampling (or case-cohort) samples the controls at the beginning from the same population from which the cases are drawn. Case-control studies are often less expensive and labor intensive to implement. A case-control is NOT a cohort study done backwards (trohoc fallacy)