The case control study: The problem and the prospect☆

Publisher Summary This chapter discusses the problem and the prospect of the case control study. The case-control study can be defined as that method of epidemiological investigation in which the frequency of an attribute or exposure to an environmental factor in cases is compared to that in non-cases or controls. The difference in the two frequencies is quantified statistically to rule out chance occurrence and to estimate the magnitude of the effect of the attribute or exposure on the disease. The case-control method of study differs from the former or the experimental method in that the investigator begins the cohort with the effect and then looks backward in time for the exposure. In the cohort and experimental modes, the investigator begins with the exposure and looks forward in time for the effect. The case-control and cohort methods depend upon observing. This is in contrast to the experiment in which the investigator is able to randomize the subjects to treatment or exposure and to manipulate one or more factors and then measure the consequences.