<prompt> The type of study that determines the norms and limits of the distribution of variables, including the characteristics of the events and population under study, is reffered to as-ExplanatoryCross-sectionalDescriptiveAnalytical  <response>: Descriptive studies are the first phase of an epidemiological investigation. Procedures in descriptive studies include: 1defining the population to be studied 2defining the disease under study 3describing the study by time , place, person 4measurement of disease 5comparing with known indices 6formulation of an aetiological hypothesis refer pgno:63 park 23 rd Edition 