Estimate of the proportion of a population which dies during a specified period. The numerator is the number of persons dying during the period; the denominator is the size of the population, usually estimated as the mid-year population. The death rate in a population is generally calculated by the formula:

10ⁿ (Number of deaths during a specified period) / (Number of persons at risk of dying during the period)

where n is usually either 3 or 5 giving rates per 1 000 or per 100 000 people in the population studied.