1. Demography
AGE and SEX STRUCTURE

2. Demography

3. Human Population inhabitants in the specific area
group of inhabitants with the same biological, cultural and social characteristics

4. AGE and SEX STRUCTURE
Population stock refers to the composition of a population at a given point in time.
While this can be broken down into many components, such as religion, marital status, ethnicity etc, demographers are primarily interested in the age-sex structure of a population.

5. AGE and SEX STRUCTURE schools, care homes maternity services etc.
E.g.
schools,
care homes
maternity services etc.
As well as determining the types of services a population will need
Age-sex structure of a population is a fundamental determinant of the numbers of demographic events that will occur such as population growth or decline and dependency ratios.

6. Dependency ratio
People in many countries are living longer. And while this is good news, it carries implications for governments and private institutions due to changes in the “dependency ratio” of countries.

7. Dependency Ratios
The dependency ratio refers to the percentage of the population too young or too old to work who are dependent on those of working age. The ratio is calculated using the formula below:

8. A mixed blessing?
An increase in the child dependency ratio – those aged under-15; may require increased spending on schooling (primary, secondary, community colleges) and maternity- based health care (day cares, clinics).
But children grow and eventually join the workforce and could ultimately tip the balance back.
Rises in the aged dependency ratio will result an increase in the proportion of citizens aged 65 and above – present special challenges to societies.
More financial support for pensions and healthcare may be needed from “the workers”, or reforms may be implemented to cope with demand.

9. Where the older people at?
Data collected by the World Bank show that richer countries have the highest aged dependency ratios.
In Japan, there were almost 34 older people for each 100 of working age in Japan’s old age dependency ratio rose from 26 in 2001 to 34 in 2009, the fastest rise of any country.
Europe is home to the top 25 countries with the highest dependency ratios. The United Arab Emirates and Qatar have the lowest ratio of 192 countries in the World Bank figures with a ratio of just one older person per 100 working age people. Ratios in the influential Group of 20 – or G-20 – countries range from 34 in Japan to five in Saudi Arabia.

10. The problem of rapidly rising dependency ratios is spreading south of the Equator. The World Bank figures show the 10 countries with the fastest rising ratios between 2001 to 2009 included
South Korea,
North Korea,
Singapore and
Puerto Rico.
Some demographers expect China to experience a rapid increase in the dependency ratio over the next few decades, as the “one child” policy over past decades will likely lead to an ageing of the population.

11. Population Growth and Doubling Time
In population studies, the growth rate is an important statistic that attempts to predict how fast the community is growing.
“Doubling time" is a common term used when studying population growth. It is the
projected amount of time that it will take for a given population to double.
It is based on the annual growth rate and is calculated by what is known as "The Rule of 70."

12. Doubling Time
To calculate doubling time, the"The Rule of 70“ is used. The formula requires the annual growth rate of the population. To find the doubling rate, divide the growth rate as a percentage into 70.
doubling time = 70/annual growth rate
Simplified, it is typically written: dt = 70/r
For example, a growth rate of 3.5 percent represents a doubling time of 20 years. (70/3.5 = 20)

13. EXERCISE
Calculate the doubling time for each country.