What is Demography

8/7/2019 What is Demography

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What is Demography?What is Demography?


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DemographyDemography Is the scientific study of human populations.Is the scientific study of human populations. AchilleAchille GuillardGuillard first used the title on his book:first used the title on his book:

Elements deElements de StatistiqueStatistique HumaineHumaine ouou DemographieDemographieCompareeComparee..

Two Greek roots:Two Greek roots:

demosdemos (people)(people)graphygraphy (branch of knowledge regarding a particular(branch of knowledge regarding a particularscience( in this case, human populations).science( in this case, human populations).

GuillardGuillard then defined demography as:then defined demography as: the mathematicalthe mathematicalknowledge of populations, their general movements,knowledge of populations, their general movements,and their physical, civil, intellectual and moral stateand their physical, civil, intellectual and moral state((GuillardGuillard 1855:xxvi).1855:xxvi).


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PopulationPopulation

thethe termterm populationpopulation refers to a collection of items,refers to a collection of items,

for example, balls in an urn (Preston et al., (2001: 1) .for example, balls in an urn (Preston et al., (2001: 1) . collection of persons alive at a specified point in timecollection of persons alive at a specified point in time

who meet certain criteria.who meet certain criteria.

For example, the population of interest may be that ofFor example, the population of interest may be that ofstudents attending a specific university during a specificstudents attending a specific university during a specific

year. In this situation, the students are born (i.e., enter)year. In this situation, the students are born (i.e., enter)

into the population when they enroll, and they die (i.e.,into the population when they enroll, and they die (i.e.,leave) when they graduate.leave) when they graduate.


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There are onlyThere are onlytwotwo ways toways to enterenter a population,a population,

bybybirthbirth and byand byinin--migration.migration.

There areThere are twotwo ways toways to leaveleave a population, bya population, by

deathdeath and byand byoutout--migration.migration. Thus, a population is often defined byThus, a population is often defined by

demographers according to the specific needs ofdemographers according to the specific needs of

the research and researcher.the research and researcher.Therefore, three processes are relevant toTherefore, three processes are relevant to

demography:demography:

Fertility, Mortality, and MigrationFertility, Mortality, and Migration!!!!!!!!!!!!


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Generally, demographers use vital registrationGenerally, demographers use vital registration(birth and death) records to count births and(birth and death) records to count births and

deaths in a population to determine fertility anddeaths in a population to determine fertility and

mortality rates. Themortality rates. The more difficultmore difficultdemographic process to measure isdemographic process to measure is

migrationmigration because in most countriesbecause in most countries

registration records are NOT maintained whenregistration records are NOT maintained whenpersons migrate into or out of the population.persons migrate into or out of the population.


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TodayToday Demography meansDemography means Is the study of the determinants andIs the study of the determinants and

consequences of population change and isconsequences of population change and is

concerned withconcerned with virtually everythingvirtually everything thatthatinfluences or can be influenced by:influences or can be influenced by:

Population SizePopulation Size

Population growth or declinePopulation growth or decline

Population processes (levels and trends inPopulation processes (levels and trends inmortality, fertility and migration that aremortality, fertility and migration that aredetermining population size and change).determining population size and change).

Population structure (how many by age)Population structure (how many by age)

Population characteristicsPopulation characteristics....


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YaukeyYaukey andand AndertonAnderton Demography:Demography:Informal:Informal:look at it in terms of Q that tries to answer:look at it in terms of Q that tries to answer:

How many people, of what kind, are where?How many people, of what kind, are where?

How come?How come?And so what?And so what?

Formal:Formal:The study of:The study of:

1)1) the size and composition of populations according tothe size and composition of populations according todiverse criteriadiverse criteria (age, sex, marital status, educational(age, sex, marital status, educationalattainment, spatial distribution, etc.)attainment, spatial distribution, etc.)

2)2) Dynamic lifeDynamic life--course processes that change thiscourse processes that change thiscompositioncomposition (birth, death, marriage, migration, etc.):(birth, death, marriage, migration, etc.):

3)3) Relationships between population composition andRelationships between population composition and

change, and the broader social and physicalchange, and the broader social and physicalenvironment in which they exist.environment in which they exist.


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Given the impact of industrialization in the reductionGiven the impact of industrialization in the reductionof fertility and mortality and the international migrationof fertility and mortality and the international migration

flows from less developed to more developed countriesflows from less developed to more developed countries

around the world, it is a common practice amongaround the world, it is a common practice amongdemographers to observedemographers to observe separatelyseparatelythe demographicthe demographic

processes inprocesses in less developed countriesless developed countries (also called(also called

developing countries) from those indeveloping countries) from those in more developedmore developedcountriescountries (also referred as developed countries).(also referred as developed countries).

The issues that concern demographers often varyThe issues that concern demographers often varydepending on the level of industrialization of eachdepending on the level of industrialization of each

country.country.


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Demographers look at issues according to level ofDemographers look at issues according to level of

development of the countrydevelopment of the country

Less developed countries:Less developed countries:

high levels of fertilityhigh levels of fertility high levels of infant mortalityhigh levels of infant mortality

a high prevalence of HIV/AIDSa high prevalence of HIV/AIDS

high levels of outhigh levels of out--migration to more developed countriesmigration to more developed countries

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More developed countries:More developed countries:

low fertility patternslow fertility patterns

women having babies at later ageswomen having babies at later ages populations with below replacement levels of fertilitypopulations with below replacement levels of fertility

and large numbers of migrants from less developed countriesand large numbers of migrants from less developed countries


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Why we care?Why we care? Infrastructure and planningInfrastructure and planning

Population structure effects in the world:Population structure effects in the world: Sub Saharan Africa young population + AIDS (lots of orphan childSub Saharan Africa young population + AIDS (lots of orphan children),ren),

Vs. North America and EuropeVs. North America and Europes older populations (Replacement level ofs older populations (Replacement level offertility, or Social Security systems in danger).fertility, or Social Security systems in danger).

Globalization:Globalization: If we know the population trends around theIf we know the population trends around theworld, marketing companies may take advantage: place factoriesworld, marketing companies may take advantage: place factorieswhere there are younger people who can work.where there are younger people who can work.

Through mediaThrough media market products to target populations according tomarket products to target populations according totheir characteristics.their characteristics.

Environment:Environment: (More resources are needed for more people)(More resources are needed for more people)

Politics:Politics: Candidates use demographics to be able to campaign inCandidates use demographics to be able to campaign intheir favor (i.e., age, sex, race, education have effects on poltheir favor (i.e., age, sex, race, education have effects on politicaliticalpreference and voting).preference and voting).

Apportionment of seats in the house of representativesApportionment of seats in the house of representatives, and the, and theallocation of tax dollarsallocation of tax dollars is based on the demographicis based on the demographic

composition of each state.composition of each state.


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A frequent concern in demography is with the extent toA frequent concern in demography is with the extent to

which changes inwhich changes in individualindividual--level behavior have anlevel behavior have aneffect on aggregate processeseffect on aggregate processes (Preston et al, 2001).(Preston et al, 2001).

More smokers at certain age in a population will have anMore smokers at certain age in a population will have an

effect on theeffect on the life expectancy at age xlife expectancy at age x and on theand on the deathdeathrate.rate.

Women getting married at older ages canWomen getting married at older ages can reduce the birthreduce the birth

raterate and put at risk the whether theand put at risk the whether the population will bepopulation will bemaintained at a replacement level of fertilitymaintained at a replacement level of fertility(which in(which in

populations with low levels of mortality is around 2.1populations with low levels of mortality is around 2.1

children per woman).children per woman).


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Formal and Social DemographyFormal and Social Demography Formal : Use as independent variables onlyFormal : Use as independent variables only

demographic variablesdemographic variables as determinants such asas determinants such as age andage andsex.sex.

Social Demography:Social Demography: Explores otherExplores other nonnon--demographicdemographicvariablesvariables as determinants such as, marital status, race,as determinants such as, marital status, race,education, socioeconomic status, occupation,education, socioeconomic status, occupation,household size, and type of place of residence.household size, and type of place of residence.

These variables are drawn mainly from sociology,These variables are drawn mainly from sociology,

economics, psychology, geography, anthropology,economics, psychology, geography, anthropology,biology, and other disciplines .biology, and other disciplines .


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Social Policy: The One Child PolicySocial Policy: The One Child Policy

in Chinain China

The sex ratio at birth is the number of malesThe sex ratio at birth is the number of males

born per one hundred females born and isborn per one hundred females born and isaround 105 in most societies.around 105 in most societies.

Since the 1980s in China it has been significantlySince the 1980s in China it has been significantly

above 105. In the year 2000 it was near 120.above 105. In the year 2000 it was near 120. The rapid reduction of fertility in China alongThe rapid reduction of fertility in China along

with the longwith the long--standing preference for sons havestanding preference for sons have

led to the selective abortion of female fetuses,led to the selective abortion of female fetuses,and a sex ratio at birth above normal levels.and a sex ratio at birth above normal levels.


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World Population Data SheetWorld Population Data Sheet

http://www.prb.org/pdf05/05WorldDataSheet_Eng.pdfhttp://www.prb.org/pdf05/05WorldDataSheet_Eng.pdf

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What is Demography