<P> In demographics , the rate of natural increase ( RNI ) is the crude birth rate minus the crude death rate . This rate excludes population increase from in migration and out migration . When looking at countries , it gives an idea of what position in the Demographic Transition Model , but to find out how much a country is growing , the population growth rate should be observed . The Demographic Transition Theory explains the rate of natural increase relate to the economic growth . </P>
when calculating the rate of natural increase one does not include
population increase from in migration and out migration