出版社：Indian Association of Preventive and Social Medicine, Gujarat
摘要：Many research questions can beanswered quickly and efficiently using data thathas already been collected. There are 3 generalapproaches to using existing database.Secondary data analysis utilizes existing data toanswer research questions other than the mainone for which the data was actually collected.Ancillary studies are the other ones that add oneor more measurements to a study often in asubset of the participants, to answer a separateresearch question. Evidence Based Medicine(EBM) utilizes existing data base systematicallyby summarizing and applying information fromthe literature to answer specific researchquestions. The main advantages of usingexisting data are speed and economy ofobtaining answers to the research questions
