Introduction to Demography

Dr. Min Ko KoM.B.,B.S, M.Med.Sc. (Public Health)

Ph.D. in Demography (Mahidol University)

Associate ProfessorHealth Behaviour & Communication DepartmentUniversity of Public Health

Ground Rules for today discussion?

1-2-3-4-5-6-7-

Outline of Presentation

I. Meaning and Scope of Demography?II. Origin of DemographyIII. Sources of Demographic measuresIV. Uses of Demography

V. Basic Measurement of Demography

What is Demography?

• Demography is the statistical study of (human) populations. • It includes the study of:

Size, Structure, Distributions and Changes over time.

By 3 Components: Birth (Fertility) Death (Mortality) People move in & out (Migration)

Analytical Demography(or) Formal Demography

I. Meaning and Scope of demography?

Scopes of Demographic Analysis

•Size :

–number of units (persons) in the population.

•Structure :

–the distribution of the population among its Age & Sex groupings. (Population Pyramid)

•Distribution :

–the arrangement of the population in space/geographical area at a given time.

•Change :

–the growth or decline of the total population or of one of its structural units.

Components of Change

• There are only 3 components of change in the population: 1) Births (B) (Fertility) increasing of pop. 2) Deaths (D) (Mortality) decreasing of pop. 3) Migration

•In-migration (IM) increasing of pop. •Out-migration (OM) decreasing of pop.

P2 = P1 + (B – D) + (IM – OM) ‘Balancing Equation

What is Demography? (cont:)

• Determinants Factors• It also includes the analysis of the relationships between

economic, social, cultural, and biological process-------------------------

Substantive Demography

Demography?Analytical Demography + Substantive Demography

influencing a population changes(Fertility, Mortality, Migration)

II. Origin of Demography

• John Graunt (1620-1674)

• -He is called father of demography because his book Natural and Political Observations Made upon the Bills of Mortality, published in1662

Bills of Mortality means ‘lists of the dead’ by plague disease.

-Weekly statistics on burials of plague -Main idea is to monitor the geographical incidence of deaths from plague.

Origin of Demography (cont:)

• John Graunt’s Observation• Vital Events • Gender Differences:

More male were born between 1628 and 1662. More Males were died earlier than females by Plague

• Life Table: • Public Health:

• Epidemiology- Plague: germs were carried by fleas that lived as parasites on rats

The scientific study of demography began with the study of mortality.

III. Sources of demographic measures

1) Vital Registration2) Survey3) Census

Vital Registration Survey Census

Data collected in continuous basic

Limitation:o Quality of Datao Data Accuracyo Age misreportingo Under reporting

Birth Death

Child Death Adult Death

Maternal D

Data collected in fixed point in timeCheaperRepresentative PopulationShort durationMore information from prepared Q:

Limitation:Nationally

RepresentativeSampling error

Data collected in fixed point in timeNationally Representative, cover whole population

Limitation:Very ExpensiveLonger durationLimited

information because of Questionnaires

VR in Myanmar• -first introduced to some parts of lower Myanmar in 1907;

and then gradually extended to other parts of the country.

• Incomplete during British colonial periods.

• Interrupted during World War II and Japanese invading to Myanmar, and didn’t resume until 1947.

• Postwar VRS are also limited to data accuracy.

• The present VRS were introduced in Myanmar in 1962 in the urban areas. The data is collected by Department of Health, Ministry of Health & Sports and compiled and published by Central Statistics Organization (CSO).

• Since 2007, VRS covers the entire population of the Myanmar

Surveys

• Eg:Demographic Health Survey (DHS)World Fertility SurveysMultiple Indicators Cluster Survey (MICS)Fertility and Reproductive Health Surveys

Surveys in Myanmar

• Fertility SurveysPopulation Changes and Fertility Survey” (PCFS)- 1991Fertility and Reproductive Health Surveys’ (FRHS

surveys)- 1997, 2001 & 2007

• Mortality SurveysOverall and cause specific under five mortality survey 2002-2003 Research Study on The Determinants of Infant and Child Morbidity

and Mortality in Myanmar 2005

• Migration Surveys

• Elderly SurveysElderly surveys 2005 and 2012

Census

• Census is the main sources of demographic data.

• A census is defined as the total process of collecting, compiling and publishing demographic, socioeconomic data pertaining, at a specific time or times, to all persons in a country or delimited territory.

• Two types of census. 1) Dejure census - counts the persons according to their usual

place of residence2) Defacto census - counts the persons where they are found

on census day.

• Both methods have some advantages and disadvantages. 1) In Dejure census, there is problem of definition of “usual

residence” because some have more residence place and some have no residence.

2) In Defacto, there is problem of counting person who travelling on census day or who works at night.

Census in Myanmar

• History of census was initiated by the era of ‘King Thadodipa Mahadamayaza of the Tagaung Dynasty’ to know the actual population of his country.

• The first Myanmar population census was taken in 1872 under the British administration covering the lower part of Myanmar; as one part of the Indian census.

• The second one was in 1881.

• Thereafter, censuses were taken every ten years since 1881till 1941; but they did not cover the entire country.

• After independence in 1948, the first nationwide population census was taken in 1973 and followed by 1983.

• The last census was performed in 2014 March/April and enumerated a total population of 51.8 millions.

• Ministry of Immigration and Population is a focal Ministry to conduct nation-wide censuses.

• Other Data Sources in Myanmar

• Department of Health Planning- makes available health statistics through its publication

Health Management Information System (HMIS) Multiple Indicators Cluster Surveys (MICS)District Health Information System (DHIS)

• Ministry of National Planning and Economic DevelopmentCentral Statistical Organization- Publishes “Statistical

Yearbooks”

IV. Uses of Demography

• Definitions

• Populations:Size -Structure (Age structure, Sex structure) -Distributions (Geographical distribution)-Changes over time (Growth/Decline)

By 3 Components:Birth (Fertility)Death (Mortality) People move in & out (Migration)

• Demography is widely used for various purposes and can encompass small, targeted populations or mass populations.

• Nation’s SE development-Eg: Life Expectancy at birth

• SE & Living Conditions

• For Governments:Political observation

• Decision Making- It provide to determine the adequate policies and plans related to population, economic, social and environment issue both at the country level and locality level.

• Policy & Planning to provide public utilities and services to the needs of people in each area

IV. Uses of Demography (cont:)

• For Scientists: use demography for research purposes,

• For Public and Private-Business Decision

• Population Projection

• Fertility-• Mortality--• Migration Migration & Health

• Other Fields -

IV. Uses of Demography (cont:)

• Why Study Demography? An understanding of population dynamics:

◦Helps explain social phenomena ◦Helps identify social needs ◦Helps plan for future needs

What dynamics are important? ◦Age structure ◦Mortality & illness ◦Fertility & birth patterns ◦Marriage and family formation ◦Migration and population movement ◦Population growth, competition for resources

Demography is the bridge from the micro to macro level

• Break! x 10 minutes

Measurements Used in Demographic Analysis

•Basic measurements: simple statistical measurements •Fertility measurements •Mortality measurements •Migration measurements

Basic Measurements

• Simple statistical measurements:

Ratio Proportion Percentage Rate Probability

Basic Measurements: Ratio

• The ratio of X to Y X Y

•Examples of ratios: Sex ratio: number of males per 100 females

Q: Sex ratio of today class?

Ratio is a single number that expresses the relative size of two numbers. The result of dividing a number of X by another number Y is the ratio of X to Y.Numerator is not included in the denominator.

Exercises

• In Myanmar, As of 2014 Census,• Male = 24225304• Female= 25987763• Sex Ratio= ??

SR of Myanmar= 93 Males for every 100 females

Basic Measurements : Proportion and Percentage

• Proportion:

X (X+Y)

• e.g. The proportion of the population under age 18 is .65

•Percentage:

X (X+Y)

e.g. The percentage of the population under age 18 is 65%

x 100

Q: Male Proportion of today class?Q: Male percentage of today class?

Basic Measurements : Rate

Rate = Number of events

Population at risk

Rate = Number of events

Person-years lived

Rate = Number of events

Mid-year population

x 1000

x 1000

x 1000

A rate is the occurrence of events over a given interval in time. Rate is used to study the dynamics of change.

Rate of incidence= #of events that occur within a given time interval/# of members of pop: who were exposed to the risk of the event during the same time interval.

Examples of Rates

•Crude birth rate (CBR):

Number of births in a year

Mid-year population

• Crude death rate (CDR):

Number of death in a year

Mid-year populationx 1000

x 1000

Population at Risk Person-Years Lived Mid-Year Population

PAR is real denominator for rate.

But, it is difficult to get the PAR.

For the reasons, PYL are used instead of PAR in denominator

The concept of PYL is ideal way to specify the PAR of an event.

It is simply the product of the number of persons multiplied by the number of years, that each person lived in a given place.PYL = no. of person x no. of year

But, the calculation of actual PYL of any Larger Size would be difficult, it is not impossible.

For the reasons, MYP are used instead of PYL in denominator

If we assume that births, deaths, and movements in and out of the population are evenly distributed throughout the year, the number of people alive at the middle of the year (July 1) would equal the number of PYL.

This population alive at the middle of the year is called MYP.

So, MYP is usually a good approximation of PYL.

Note: (if B,D,M are not evenly distributed, we cannot apply as MYP = PYL)

Calculating Mid-Year Population

•Mid-year population

= (P1 + P2) / 2

= [P1 + (P1 – D)] / 2

= P1 - ½ D

= P1 – ½ (P2 – P1)

• where:

• P1 = population on 1st January

• P2 = population on 1st January next year

• D = Deaths in a year

Q: Which formula is easy to memorize?

Basic Measurements : Probability

Number of events

Population at the beginning

•Ranges between 0 and 1

•Measured during a fixed period

• e.g. Probability of dying at age 25:

Number of deaths at age 25

Number of people who reach age 2

Probability is similar to a rate, with one important difference.

The denominator is composed of all those persons in the given pop: at the beginning of the period of observation

What you learned today?

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More Readings

• PALMORE, J. A. & ROBERT W. GARDNER. 1983. Measuring Mortality, Fertility, and Natural Increase: A Self- Teaching Guide to Elementary Measures. Honolulu: The East-West Center. Chapter I (p.1-7)

• ROWLAND, D.. 2003. Demographic Methods and Concepts. Oxford : Oxford University Press. Chapter I (p.13-44)