Understanding how population changes over time is an important science. This lesson takes a look at the rate of natural increase in population and how to calculate it.
You will also get a clearer understanding of why this matters.
Natural Increase in Population
Tommy is a student studying sociology. Today his professor is instructing on populations, specifically how and why they increase.
Tommy is a great student, and he’s easily able to follow along with the professor when she explains that the natural increase in population (NIP) is defined as the crude birth rate (CBR) minus the crude death rate (CDR). Just to fill you in, CBR is the number of live births for every 1,000 people in a given population. Similarly, CDR is the number of deaths for every 1,000 people in a given population.In other words, NIP is how much the population is going up or down, based on how many people are being born or dying, not taking into account when people move.After talking awhile about NIP, the class moves on to discussing how to figure out the rate. The formula for calculating the natural increase in population is:CBR – CDR = NIPRemember, CBR = crude birth rate, CDR = crude death rate, and we’re always looking at those rates for every 1,000 people in a population.
While Tommy catches on right away, his seat partner is struggling, so the professor comes up with an example to help the class better understand.
She tells the class that for 2014, the estimated US crude birth rate was 13.42 and the estimated crude death rate was 8.15. What is the estimated rate of natural increase in population for the US in 2014? Let’s take a look at how we plug in these numbers.13.42 – 8.15 = 5.
27Since the calculated number is births per 1,000, and we want births per 100, so that we can express the answer as a percentage, simply divide by 10.5.27 / 10 = 0.527%As you can see, the rate of natural increase in population for the US is fairly small. The professor tells the class this is typical of developed countries.
In fact, some developed countries even have a negative rate of natural increase. Germany, Japan, Italy, and Russia are among the countries that had estimated negative natural increases in population for 2010.Underdeveloped countries, particularly in Africa, tend to have very high rates, as much as 7 times higher than the United States in 2010.
This is because the birth rate in underdeveloped countries is high due to a lack of education for women and low access to birth control.
Why Call It Natural?
Tommy has one question that’s been bugging him: why is it called a ‘natural’ rate? The professor explains that ‘natural’, in rate of natural increase in population, just means that it only takes into account birth and death rates. It specifically does not take into account population changes due to people moving in or out of the region.
How Is This Information Useful?
The bell is about to ring and the professor wants to squeeze in one more thing. She explains why scientists want to figure out NIP by telling the students that making an accurate prediction of the future population, and demographics of that population, is useful for many professions and organizations.
Local, regional, and national governments; population scientists; the World Health Organization and International Monetary Fund are all examples of entities that use future population estimates in the decisions they make today. The better the estimates of that future population are, the better the decisions these organizations can make.
As Tommy found out in his class, the rate of natural increase of a population is found by taking the crude birth rate (CBR) and subtracting the crude death rate (CDR). This rate is ‘natural’ because it does not include changes in the population due to the movement of people. A negative rate, or one lower than about 10 per 1,000, typically indicates a developed country, while higher rates are generally found in less developed parts of the world.
Many organizations use NIP information to predict future populations and make policy decisions based on those estimates.