<prompt> Experimental studies are meant to -Test etiological hypothesisFind out prevalence ratesFind out cause of epidemicsTo find out the history of disease  <response>: Experimental studies involve an active attempt to change a disease determinant or the progress of a disease and are similar in design to experiments in other sciences. The major experimental design is randomized control trials. Field trials and community trials are other experimental studies. refer pgno:63 park 23 rd edition 