Part 3: Analyzing World Population Trends Demographic Transition Model & Population Pyramids

Demographic Transition Model

• Demographic Transition (DT) is the transition from high birth and death rates to lower birth and death rates as a country or region develops from a pre-industrial to an industrialized economic system.

• Birth rate refers to the number of births that occur per thousand people, per year.

• Death rate refers to the number of deaths per thousand people, per year.

• Using the Demographic Transition Model (DTM), demographers can better understand a country’s current population growth based on its placement within one of five stages .

• That data is then passed on to be used for addressing economic and social policies within a country and across nations.

Demographic Transition Model

Demographic Transition Model (DTM)

• Within the model, a country will progress over time from one stage to the next as certain social and economic forces act upon the birth and death rates.

• Every country can be placed within the DTM, but not every stage of the model has a country that meets its specific definition.

• For example, there are currently no countries in Stage 1, nor are there any countries in Stage 5, but the potential is there for movement in the future.

What are the Stages of the DTM?

• In Stage 1, which applied to most of the world before the Industrial Revolution, both birth rates and death rates are high. As a result, population size remains fairly constant but can have major swings with events such as wars or pandemics.

• In Stage 2, the introduction of modern medicine lowers death rates, especially among children, while birth rates remain high; the result is rapid population growth. Many of the least developed countries today are in Stage 2.

• In Stage 3, birth rates gradually decrease, usually as a result of improved economic conditions, an increase in women’s status, and access to contraception. Population growth continues, but at a lower rate. Most developing countries are in Stage 3.

What are the Stages of the DTM?

• In Stage 4, birth and death rates are both low, stabilizing the population. These countries tend to have stronger economies, higher levels of education, better healthcare, a higher proportion of working women, and a fertility rate hovering around two children per woman. Most developed countries are in Stage 4.

• A possible Stage 5 would include countries in which fertility rates have fallen significantly below replacement level (2 children) and the elderly population is greater than the youthful population.

Demographic Transition Model

Demographic Transition Model

Demographic Transition Model

Demographic Transition Model

• Like any model, there will be outliers and exceptions to the rule and the Demographic Transition Model is no different.

• There are things the DTM cannot reveal:

• the impact of other demographic variables such as migration, are not considered,

• nor does the model predict how long a country will be in each stage.

Exceptions to the DTM

Population Pyramids

• A Population Pyramid is a graph that shows the age-sex distribution of a given population.

• It a graphic profile of the population’s residents.

• Sex is shown on the left/right sides, age on the y-axis, and the percentage of population on the x-axis.

• Demographers use population pyramids to see population trends in the past, examine the current resident profile, and also to project how the population will increase/decrease in the future.

Population Pyramids

• The more rectangular the graph is shaped, the slower a population is growing;

• We see a more uniform population size across age groups.

• Old generations are being replaced by new generations of approximately the same size.

• The more a graph looks like a pyramid, the faster that population is growing;

• Old generations are producing larger new generations.

• Another way to think of it is that the pyramid shape has a larger bottom than top; a larger percentage of the population are in their reproductive years or haven’t even reach reproductive age. As a result, there is much potential for growth.

Population Pyramids

Complete questions analyzing population growth trends