What is Demography?

Demography is a component of Human Geography. It is the study of population and people, focusing on size, growth, density, distribution and trends over time and space.

Data Collection Methods

Most countries collect some kind of data on the social, economic and demographic conditions of the population. This vital data is collected for a number of reasons. It allows central and local governments along with health and education authorities  target their resources more effectively and to plan housing, education, health and transport services. There are two ways demographic data is typically collected: National Census Taking and Vital Registration.

Demography is the study of human populations and their spatial distributions. Here, racial data from the U.S. 2010 census is plotted on a map.

National Census Taking is a static measure of population as it takes a single snapshot of the national population, usually down to the local level. Social and economic data is collected every 10 years and involves the completion of a questionnaire by each household. Questionnaires generally ask about the composition of the household and financial status. Everyone in the country is under an obligation to complete a census form, and a limited number of people are prosecuted for failing to comply with this obligation.

A national census is extremely important for governments as it allows them to project future demands for jobs, enables planning for services (e.g., schools and hospitals) and enables the projection of national housing demands. It also enables services to be located close to demand, assists provision of essential utilities, and helps identify under-served locations.

Vital registration is a dynamic way of collecting population data, where the number of deaths and births within a country is monitored frequently. This mini-census can be completed at town halls or government buildings on a daily basis. In years of non-census taking, the total population can be estimated using the information from vital registration. It gives a continuous record of population whereas the census gives a snapshot of the population every few years.

Changes to population over time

The Demographic Transition Model (DTM) describes population change over time using population data that has been collected from countries. The DTM was designed by Geographer Warren Thompson in 1929, who observed changes in birth and death rates in industrialized societies over two hundred years. His belief was that there were 5 stages to the DTM which illustrated different changes to birth rates, death rates and total population change. Birth rate is the number of live births per 1000 in a year, while death rate is the number of deaths per 1000 in a year. The total population will grow if the birth rate is above the death rate, creating natural increase. However, if the death rate is above the birth rate then the population will fall, leading to natural decrease.

demographic transition model
The demographic transition model (DTM). Source: BBC.

In stage 1, the high stationary stage, birth and death rates are both high; above 35 per 1000. Population growth is slow and fluctuating, while life expectancies are short. Birth rates are high because of a lack of family planning, religious beliefs and need for workers in agriculture. Due to high infant mortality rates, children died at an early age so families would have more in the hope of some surviving to adulthood. Death rates were elevated due to high levels of diseases, famine, lack of clean water and sanitation and a lack of health care. Stage 1 examples would include remote tribes such as those still living in the Amazon.

Stage 2, the early expanding stage, illustrates a birth rate which remains high and a death rate that is falling, so the population begins to rise steadily. Because the birth rate is above the death rate, natural increase will occur, resulting in population growth. Death rates fall due to improved healthcare where there is access to vaccines and other treatments, as well as improved hygiene and sanitation. There is also an increase in food production as the country becomes more developed, resulting in greater dietary nutrition and survival. The birth rate remains high due to the same reasons as Stage 1. Global examples of this would include Egypt and Kenya.

Stage 3, the late expanding stage, shows a birth rate which is beginning to fall to 20 per 1000 while the death rate continues to fall faster to 10 per 1000. As a result, the population overall continues to grow. The death and birth rates fall due to a number of reasons. With more family planning available fewer children are born. As women’s role in society change, and they begin earning a living, fewer opt to have children, leading a declining birth rate. Improvement in sanitation and health care supports rising standards of living and falling death rates. Stage 3 is evident is Brazil, for example.

The low stationary stage, stage 4, has both low birth and death rates below 10 per 1000. This leads to a stabilizing of the population. Both low birth and death rates are attributed to strong economies, emancipation of women, highly educated populations, and strong health care systems. Most developed countries have reached stage 4 such as USA and UK.

Stage 5, the declining stage, is a relatively new theory. It is believed that as birth rates are low, and life expectancy has increased, the death rate begins to fall as there are a higher percentage of aged persons in the population. When this occurs, the death rate will be higher than the birth rate, leading to natural decrease. The population will actually begin to fall. Due to high costs of raising a family, later marriages and raising standards of women in employment, birth rates decline well below historical figures. Germany and France are two countries where it is believed that there is natural decrease occurring. The population of the U.S. would also have begun to fall slightly if it wasn’t for continued immigration.

Like all models, the DTM has limitations. There is no consideration of the forces that might influence migration and it assumes that all countries will go through the same developmental pattern. Thompson based his theory on industrialized countries, following the pattern of European nations, but now because of globalization and foreign aid, many developing countries have transitioned through the stages at a much faster rate. Also, the model does not predict how long a country will be in each stage.

The Importance of Demography

At present, the world’s population is approaching 7.6 billion, and shows little sign of leveling off in the near future. It’s therefore vital that we have an understanding of the demographic composition and trends of all the world’s nations. It is important to know the birth rate, the death rate, and migration statistics. This information is critical if we are to effectively and predict and prepare for future change on an increasingly constrained planet.

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