Bias in case-control studies

Case-control studies are largely used to explore differences between groups of individuals. They can identify potential risk factors associated with disease, or they can investigate patient behaviour, such as why some people do not attend for services. As such, case-control studies are often used to generate or test hypotheses about causal factors. Nonetheless, bias is always a danger in case-control studies, arising especially from the way in which study samples are selected or from the collection of retrospective data. Confounding also remains a problem. This short paper explores ways in which such flaws can be uncovered in published studies.