True of case control studies

<p>case control studies usually known as retrospective studies.are those which proceeds from efect to cause .it mainly involves two study populations cases and controls.they are basically comparison studies from which the"odds ratio" can be calculated.focus is on a health problem that has already occurred.not much patients are required for the study.ODDS RATIO is a measure of the strength of association between risk factor and outcome.it is closely related to relative risk.</p><p>ref:park&;s textbook of preventive and social medicine,22 nd edition ,pg no 68</p>