Epidemiologic Study design Essay Example | Topics and Well Written Essays - 500 words

Epidemiologic Study design - Essay Example This study design finds good application in epidemiology for investigating conditions which are relatively rare and in conditions with long latency periods. A researcher performs analysis by looking back in time to evaluate the case and control groups in terms of exposure history and indication of characteristics that may put the subjects at risk for developing the condition under study. Analysis is conducted under the assumption that differences in the history of exposure will explain the occurrence of more cases than controls (Portney and Watkins, 2009). The two main strengths of case-control studies are: ease in gathering subjects, and their utility to provide estimates which may support causal relationship between risk factors and the condition (disease) in combination with other evidences (Portney and Watkins, 2009). Case-control studies are, somehow, limited in the sense that there is a possibility of uncertainty in the temporal relationship between the exposure and the condition (disease). Another limitation in this type of study design is that the proportion of cases and controls in the study is not related to the proportion of cases and controls in the population. Case control studies require further analysis pertaining to the potential for bias (Portney and Watkins, 2009). Moreover, in a case-control study design, control of selection is difficult; it may be applied to the study of only one disease outcome at a time and is usually subject to recall bias (Jekel, Katz and Elmore, 2001). In a case-control study, neither absolute risk nor odds can not be measured since â€Å"it is only possible to calculate risk in a study where subjects have been followed forward in time† (Daly and Bourke, 2000, p. 166). However, Daly and Bourke (2000) revealed that â€Å"the cross-product ratio in a case-control study, which legitimately estimates the ratio of the odds of exposure, must also be a valid estimate of the ration of