Descriptive studies include '''censuses''' and '''surveys''', and are essential in the investigation of the levels of disease in populations, as well as in the crude monitoring of the effect of an intervention or exposure to a risk factor. In a purely descriptive study, no attempt is made to formally investigate reasons for the patterns of disease observed, although hypotheses regarding possible reasons will commonly be generated and developed as a result of these investigations. It is of vital importance that the ''source population'' of a descriptive study is clearly defined (in terms of animal, place and time), and that forms of ''selection bias'' are minimised, in order to allow accurate inferences to be made based on the results. These concepts are covered in other sections. | Descriptive studies include '''censuses''' and '''surveys''', and are essential in the investigation of the levels of disease in populations, as well as in the crude monitoring of the effect of an intervention or exposure to a risk factor. In a purely descriptive study, no attempt is made to formally investigate reasons for the patterns of disease observed, although hypotheses regarding possible reasons will commonly be generated and developed as a result of these investigations. It is of vital importance that the ''source population'' of a descriptive study is clearly defined (in terms of animal, place and time), and that forms of ''selection bias'' are minimised, in order to allow accurate inferences to be made based on the results. These concepts are covered in other sections. |