Translations:Advanced Field Epi:Manual 1 - Disease Investigation/302/en

Case-control studies do not have a population at risk. They are based on selection of cases and a separate selection of non-cases (controls). As a result case-control studies cannot be used to produce prevalence or incidence measures. Because of this, they cannot be used to produce relative risk measures. Data from case-control studies can produce odds ratios and these are the primary measure of strength of association for case-control studies. Case-control studies are particularly useful for studying rare diseases because cases can be detected and then enrolled in the study along with one or more controls.