Session 8:Cencus
Instructor: Wu Fan
[email protected]
Age structure of a population
• Population aging is defined as the increasing
proportion of older persons in total population.
• Population ageing is a shift in the distribution of
a country's population towards older ages. This
is usually reflected in an increase in the
population's mean and median ages, a decline in
the proportion of the population composed of
children, and a rise in the proportion of the
population that is elderly.
China: Sex Ratio at Birth by Province, 2000
Source: Tabulation on the 2000 Population Census of the People's Republic of China, Vols. I & III, Population Census Office
under the State Council & Department of Population, Science, and Technology Statistics, National Bureau of Statistics of China
(China Statistics Press: Hong Kong, 2001), Table 6.1.
Factors of High SRB
• Son preference/ sex discrimination and
gender segregation
• Traditional culture
• Family planning policy
• Sex selection techniques/ B-ultrasound
instrument/sex-selective abortion and
infanticide
Sex structure of a population
• Sex Ratio Represents the Number of Males to Females in
a Population
• Sex ratio is the demographic concept that measures the
proportion of males to females in a given population. It
is usually measured as the number of males per 100
females.
• The ratio is expressed as in the form of 105:100, where
in this example there would be 105 males for every 100
females in a population.
• Sex ratio at birth/出生性别比: normal range between
102-107
Age structure of a population
• It describes the distribution of the population according
to age group (0-14 years, 15-64 years, 65 years and
over).
• The age structure of a population affects a nation's key
socio-economic issues.
• Countries with young populations (high percentage
under age 15) need to invest more in schools, while
countries with older populations (high percentage ages
65 and over) need to invest more in the health sector
• Countries with the rapid growth of a young adult
population need to more employment opportunities.
•
Population Structure:
China, 2000 vs. 2025 (projected)
90-94
2025
2000
2025
2000
75-79
60-64
45-49
30-34
15-19
0-4
80000
60000
40000
20000
0
20000
40000
60000
80000
Source: Population Division of the Department of Economic and Social Affairs of the United Nations
Secretariat, World Population Prospects: The 2002 Revision and World Urbanization Prospects:
The 2001 Revision, http://esa.un.org/unpp, 25 April 2003; 2:57:12 PM.
Consequence of different population pyramids
• A broad base population pyramid means/
expansive population pyramids:
–
–
–
–
–
–
increase food production
build more homes & schools
plan for more job opportunities for the young in future
implement birth control programme/campaigns
Usually agricultural with problems of overpopulation.
Many Dependents
An example of stationary population pyramids
Consequence of different population pyramids
• A narrow based population pyramid
means/constrictive population pyramids :
– Birth rate and Death rate low
– Work out incentives to encourage more births
– hiring foreign labour
– proper medical services & health care for the
aged
• A series of age-sex pyramids can show how
births, deaths and migration changes the
composition of each cohort in the population
over time.
• It can also inform projections of the likely future
shape of that population.
census
• Census refers to the national unity organize a statistical
investigation to domestic population within the prescribed
time ,with the unified method ,item and questionnaire.
Census work
• Census work including
– the census data collection
–
–
–
–
data analysis
Evaluation
editing
publishing process
• one of the most basic scientific method of the data collection
of world population that is widespread adopted
• the main source to provide the basic data of population.
The features of census
• universality:Regional scope of census is a national scope. In general
the regional scope of permanent, everyone should be surveyed.
• Unity:the government or census bureau set the prescribed time, unified
questionnaire, unified object, item and method.
• Individuality:the personal data should be declared directly. If not, each
one should be designated by the people familiar with the situation on
behalf of the facts.
• periodicity:a census every ten years. An afterwards census every five
years. (sampling 1% of the population to make a supplementary data)
Objection of census
• the resident population:the population that often live in
one residence, usually longer than a half year.
• existing population:all the population in an area within the
census time.
• register population:the population register in a region. It is
also called Legal population.
• The objection of census are the resident population and
existing population.
• July 1st 1953----the first census
• July 1st 1964----the second census
• July 1st 1982----the third census
• July 1st 1990----the forth census
• November 1st 2000----the fifth census
• November 1st 2010----the sixth census