Population Change is the change in the number of people during a specific time period. The change may be caused by natural deaths, births, immigration, or emigration. The rate of population change can be measured by birth rate, death rate, or net migration rate.
There are two types of population change: natural increase and migration. Natural increase is the number of live births minus the number of deaths. Migration is the movement of people into or out of an area for other than a year.
A positive population change, when the result of net migration plus live births minus deaths is positive, is referred to as population growth, a negative one is called a population decrease.
The crude rate of population growth is the ratio of total population growth during the year to the average population of the area in question that year. The value is expressed per 1 000 inhabitants.
