Case-Only Design

Analytical studies are designed to test the hypotheses created by descriptive studies and to assess the cause–effect association. These studies are able to measure the effect of a specific exposure on the occurrence of an outcome over time. Depending on the nature of the exposure, whether it has been caused experimentally as an intervention on the study subjects or has happened naturally, without any specific intervention on the subjects, these studies may be divided into two major groups: observational and experimental studies. Each of these designs has its own advantages and disadvantages. In observational studies, by definition, the researcher is looking for causes, predictors, and risk factors by observing the phenomenon without doing any intervention on the subjects, whereas in experimental designs, there is an ...