Population change can also be described as population growth. This is the increase (positive growth) or decrease (negative growth) in the number of the people. Change in the population is caused by birth, death and migration;-
1. Birth rate;- A high birth rate coupled with a low death rate result in a positive change in population. This translates into an increase in population. A high birth rate is caused by high fertility and fecundity within a population.Fertility is defined as the ability to conceive or to reproduce.
2. The Crude Birth Rate:- The crude birth rate is estimated rate of births in a year. It is not a precise figure because the values for the total population that are used for the calculation are an estimate as by the middle of the year.
3. Death rate;- This factor is sometime expressed as mortality and it refers to the number of deaths within a given population. There are three types of death rates.
- Infant Mortality Rate. Is the number of deaths in the first year of life per one thousand live births.
- Child Mortality Rate. Is the number of deaths of children aged between 1 and 5 years per one thousand live births.
- Adult Mortality Rate. Refers to the number of adult dying per one thousand of the total population.