RETROSPECTIVE DESIGNS

INTRODUCTION: Studies with a retrospective design are ones in which a phenomenon existing in the present is linked to phenomena that occurred in the past, before the study was initiated. That is, the researcher is interested in a present outcome and attempts to determine antecedent factors that caused it. For example, most of the early epidemiologic studies of the link between cigarette smoking and lung cancer were retrospective.

STARTING POINT RETROSPECTIVE STUDIES: In such a study, the researcher begins with groups of people with and without lung cancer (the dependent variable). The researcher then looks for differences between the two groups in antecedent behaviors or conditions. Retrospective studies are often cross-sectional, with data on both the dependent and independent variables collected once, simultaneously.

INCORPORATION OF STUDY DESIGNS: Researchers can sometimes strengthen a retrospective design by taking certain steps. For example, one type of retrospective design, referred to as a case-control design, involves the comparison of cases or subjects with a certain illness or condition, such as lung cancer victims, with controls for example, people without lung cancer. In conducting a strong case-control study, researchers find the cases and obtain from them information about the history of the presumed cause. Then the researchers must find controls without the disease or condition who are as similar as possible to the cases with regard to key extraneous variables such as, age, gender, and also obtain historical information about the presumed cause.

If controls are well chosen, the only difference between them and the cases is exposure to the presumed cause. To the degree that researchers can demonstrate comparability between cases and controls with regard to extraneous traits, inferences regarding the presumed cause of the disease are enhanced.

RELATED;

1.  THE RETROSPECTIVE-PROSPECTIVE STUDY DESIGN

2.  CROSS-SECTIONAL STUDY DESIGN

3.  RESEARCH METHODOLOGY

REFERENCES