|Epidemiology is the branch of medical science that investigates all the factors that determine the presence or absence of diseases and disorders. that deals with the study of the causes, distribution, and control of disease in populations. Much of the data that epidemiologists collect comes from self-report from answers provided by people participating in a study. Peer review refers to the work done during the screening of submitted manuscripts and funding applications. This process encourages authors to meet the accepted standards of their discipline and reduces the dissemination of irrelevant findings, unwarranted claims, unacceptable interpretations, and personal views. Publications that have not undergone peer review are likely to be regarded with suspicion by academic scholars and professionals.