Section 3

• Presentation of data• Sex ratios • Son preference• Dependency ratios• Population aging

Age and sex structure• This is the distribution of the population by age and sex within a given

year.

• The structure of the population is worth studying because different groups in the population have different needs.

• Different groups are more at risk of experiencing a particular demographic event. ( females 15-49 the risk of a maternal death)

• Help us to identify and predict changes in the population over time. Provides us with a quantitative basis for policy analysis and formulation

• Education, social security,health, employment, housing.

•

• Age data is collected by single year of age • But present in 5 year cohorts to make

analysis easier

• 0-4• 5-9• 10-14• 15-19

Groups in the population • <1 year infant• 0-18 children• 10-19 adolescents• 15-24 youth • 10-24 young people• 0-14 dependent young• 15-64 working age• 65+ or 60+ elderly• 60-74Young elderly • 75+ Old elderly• 80+ disabled elderly

Classification of populations• Populations may be classified based on the

relative proportions in the young and elderly cohorts

• Young population has 35% of its members under age 15 years

• Old population has 10% of its members over 65 years.

• Problem may arise when a population exhibits both characteristics.

• The median age allows for a mutually exclusive classification.

Median age

• The age that divides the population in half.

• Population with a median age • < 20 years is a young population• 20-29 is a population of intermediate ages• 30+ is an old population

Sex ratio

• This is the proportion of males in the population per every 100 females

• Cal: males X 100 Females

Barbados 1960 105519 X 10012681183.20 males per 100 females

Barbados 1990118556 X10012873092.0 males per 100 females

Patterns in sex ratio • Shows a constant pattern for most countries

• Usually highest at birth, about 102-105 males per 100 females.

• Although more male babies are born than female babies, the probability of dying at birth (< 1 year) is higher for male children

• This causes the sex ratio to fall steadily with increasing age. The sex ratio is almost even in the early adult years and decreases further in old age.

• During old age the ratio is at its lowest as life expectancy is on average 3-5 years higher for females

• Men mature slower and die earlier than women

CHANGES IN THE SEX RATIO IN JA

Age group

1943 1970 1991 2000

Total 93.7 95.5 96.2 96.9

0-4 100.3 101.6 103.2 103.7

5-14 100.8 101.0 101.3 102.6

15-29 87.8 92.8 95.1 96.0

30-44 97.2 89.1 93.7 92.2

60+ 76.2 83.9 84.1 86.5

Determinants

• Affected by relative patterns of • Births• Deaths • Migration• However, these patters must show greater

selectivity of a given sex (biased towards M or F)

• Major wars also lower the sex ratio

Son preference

• The tendency for parents to prefer male children over female children

• where son preference is strong, mortality for girls in the second to fifth year of life after birth is higher than that of boys

• Where fertility is high couples may continue to have more children than they want as they attempt to get a son.

• Where fertility is low selective abortions and female infanticide is common

Manifestations of son preference

• Female infanticide• Female neglect • Boys being better fed• Given earlier medical attention for illness • Other favorable attention

Why are male children preferred over females?

• Old age security

• Needed to perform certain religious rituals

• Status

Countries • In Eastern Asia, son preference is strong and

fertility low.• In China and Republic of Korea 110 boys per 100

females.• At least 60 million girls who would otherwise be

expected to live are missing due to selective abortions or relative neglect

• Laws in India and China ban sex-determination testing .

• Need to increase the status of women

Dependency ratio

• This is a measure of the economic burden shared by the working age population.

• the ratio gives us the number of persons in the population who are theoretically dependent on the working age population for economic and social support.

Population groups

• youth dependents- persons 0-14 yrs

• Old age dependents – persons 65+ yrs

• Working age population – 15-64 yrs

Calculation

• Total dependency ratio

Population 0-14 + 65 and over X100

Population 15 – 64

Barbados 1980

78.0 dependents per 100 persons in the working age group

Youth dependency ratio

• Youth dependency ratio

Population 0 -14 X100

Population 15 – 64

Barbados 1980

52.6 youth dependents per 100 persons in the working age group

Aged dependency ratio

• Aged dependency ratio

Population 65 and overX100

Population 15 – 64

Barbados 1980

25.4 dependents per 100 persons in the working age group

Problems • Not all persons in the dependent age group

are dependent• Some children are working• Elderly may still be employed or live on

their savings.• Some persons in the working age group are

not working

Advantages

• Gives a rough estimate of the economic burden shared by the working age pop

• compare changes in populations over time• Gives us an indication of how rapidly the

population is aging• Young populations will have a high dependency

ratio • A ratio of 1 means that the working age population

is carrying a heavy load. Especially