Factors Affecting Population Change
There are four factors that affect population change in a country:
1) Birth Rate-the number of live births per 1000 in a year
Birth rates are affected by such factors as nutrition, fertility, attitudes about abortion, labour value of children, government policies, social value, the availability of contraception and culture.
2) Death Rate-the number of deaths per 1000 in a year
Death rates are affected by disease, war, medical technology, improved health care, transportation development and nutrition.
3) Immigration-the number of people moving into a country.
Pull factors-characteristics of a place that attracts people to it.
4) Emigration-the number of people leaving a country
Push Factors-characteristics of a place that causes people to leave.
Refugees- people who are forced to leave their country due to war, life-threatening discrimination, famine, or natural disasters.
Population Growth Rate – The percentage increase in a population over a period of time. Calculated by subtracting the number of deaths + emigrants from the number of births + immigrants.
Replacement Level – The number of children required to keep the population of a country constant, not taking migration into consideration. This is about 2.1 children per female in MDCs and 2.5 children per female in LDCs.
Total Fertility Rate – The average number of children a woman has in her lifetime in a country. This obviously depends on religion, culture, social values and economic status.
Rate of Natural Increase (RNI) – birth rate minus death rate, calculated as a percentage; this does not take migration into consideration
RNI (%) = BR - DR
(in order to get a % you must divide by 10 because BR and DR are measured per 1000)
Doubling Time – The time in years needed for a population to double its size assuming the growth rate remains the same.
DT (years) = 70