|Epidemiology is the study that deals with the occurrence, distribution and cause of the disease in a population. In this group of people are studied rather than the individual person. Epidemiology field can be divided into two categories- descriptive epidemiology and analytic epidemiology. In descriptive epidemiology a survey is done of the population to see that which segment of the population is affected by a disorder, the changes or variations observed or mortality over time and in different locations, and this study helps in the identification of syndrome or suggest associations with risk factors. In analytic epidemiology studies are conducted to check the conclusions of descriptive surveys or laboratory observations. The collected data on diseases is then used to find those at high risk, identify the cause and take possible preventive measures, and plan new health services.
Major areas of study that comes under epidemiological study are disease etiology, outbreak investigation, biomonitoring, disease surveillance and screening, and comparisons of the effects of treatment given in clinical trials.
The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.