Glossary of Terms Incidence is the number of new cases of a disease in one year divided by the population at risk. Infant mortality rate is the number of deaths of children under one year of age divided by the number of live births, usually expressed as deaths per 1,000 births. Mean is an average obtained by taking the sum of the group and dividing by the total number in the group. Median is the middle value of the distribution. It usually has the same number of items above and below it.
Morbidity is the number of cases of the disease in a population at one time.
Mortality is the number of deaths divided by the population in which they occur. Prevalence is the proportion of people who have the disease at one point in time. Vital statistics are the statistics relating to life and death, e.g., birth rates, death rates, marriage rates, mortality, morbidity, population counts. All rights reserved.