Demographic Transition Model and Population Structure Analysis
Demographic Transition Model
This model explains the evolution of a population through various phases based on demographic indicators:
Initial Phase (Late 18th Century)
Characterized by high birth rates and high mortality rates, resulting in low population growth.
Transition Phase (19th – Early 20th Century)
Currently seen in some underdeveloped countries. The mortality rate drops while the birth rate remains high. Subsequently, both indicators decrease, and natural growth is reduced.
Late Transition Phase (Mid-20th Century)
Countries undergoing development. Birth rates and mortality rates become very low, so natural growth is minimal.
Regression Phase (Late 20th Century – Present)
Currently seen in developed countries. The evolutionary phase of the transition regime gives way to a new phase characterized by a low birth rate and an increasing mortality rate due to the aging population. Natural growth is weak and can even be negative.
Not all countries have progressed through this model equally. While many industrialized countries are in the regression phase with falling populations, the least developed countries are generally still in the transition phase.
Spatial Population Movements
These are the movements people make. They include:
Habitual Movements
These movements are repeated regularly and do not imply a change of job or residence. We can distinguish:
- Pendulum Movements: These occur when studying or working in a different location from one’s residence.
- Leisure-Related Movements: These are displacements that take place during weekends, holidays, and vacation periods.
Migrations
These shifts represent a change of work and residence by those carrying them out. We distinguish between emigration (people leaving a certain area) and immigration (people arriving in a certain area).
Types of Migration
- Internal Movements: Produced within a country. Among internal movements is the rural exodus, or the displacement of large populations from the countryside to the city.
- External Movements: Occur when people move from one country to another.
- Net Migration: The difference between the number of immigrants and emigrants in a given place and time.
Population Structure Analysis
The population structure is defined by biological traits (age and gender), economic factors (employment or work activity), and cultural aspects (literacy).
Population Structure by Age
Based on age, the population is usually arranged into three groups:
- Youth (0-14 years): Aging populations have a low percentage (e.g., under 15%), while young populations have a large proportion (e.g., over 40%).
- Adults (15-64 years)
- Seniors (65 years +): Aging populations have a high percentage of elderly (e.g., over 12%).
The age structure helps distinguish between young and aging populations.
Population Structure by Sex
Around the world, slightly more boys are born than girls, but female life expectancy is generally higher than male life expectancy.
Population Structure by Work Activity
We can distinguish between:
- Labor Force: The group of individuals who are of working age (typically 16-64 years), whether they perform any gainful occupation or are unemployed and seeking work.
- Inactive Population: Consists of those unable to work because they are minors or retired, or those who do not perform paid work (e.g., homemakers, students).
Population Structure by Education Level
The population can also be classified according to the degree of literacy.