1- Overview of Demographic Concepts

8/2/2019 1- Overview of Demographic Concepts

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Overview ofDemographic Concepts

Josefina N. Natividad, D.Sc

TrainingCourseonBasicDemography

RichvilleHotel,MandaluyongCity


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SourcesofPopula.onData

Popula'onDataismainlyobtainedthruthe

followingsources:

1.Census2.VitalRegistra'onSystem3.SampleSurveys4.Administra'veRecords


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Census Thisisacompleteenumera'onorcountofpopula'on

thepopula'onresidinginapar'culararea

ItisconductedbytheNa'onalSta's'csOfficeforapar'cularappointed'meindesiredintervals(usually5

or10yearintervals)

ThelatestcensuswasconductedinMay17,2010.



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VitalRegistra/onSystem TheNa'onalSta's'csOfficethruthelocalcivilregistrars

collectsinforma'ononvitaleventssuchas Births Deaths Marriages

Includinginstanceswhenmaritaldissolu'onoccurs


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SampleSurveys Usesasampleofthetargetpopula'ontoproduce

es'mates

Maybeconductedforthena'onalorsub-na'onalscaleSomeexamplesinclude:

Na'onalDemographicandHealthSurveys(NDHS), FamilyIncomeandExpenditureSurvey(FIES), LaborForceSurvey(LFS),amongothers.



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Administra/veRecords

Informa'onisbasedontheopera'onsofthepar'cularcollec'ngagency

Someexamplesinclude:

Educa'onperformance(DepartmentofEduca'on) Immuniza'on (DepartmentofHealth) Voterprofile (CommissiononElec'ons)


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Popula.onSize

Thisreferstothetotalpopula'onofapar'cularsizelocalityorterritoryataspecific'meperiod.

Totalpopula'onincludesallpersonslivinginprivatehouseholdsandthoselivinginins'tu'onalquarterslikeprisons,dormitories,hospitals,hotels,etc.,aswellasthosewhoareinembassies,

consulatesandmissionsabroad.

Land-basedOverseasFilipinoWorkers(OFWs)areincludedinthetotalcountaslongastheyfallwithinacut-offreferenceperiod

(usually5years).

Seafarersareincludedinthetotalpopula'oncount.


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76103

160192

271

367

421

481

607

686

765

886

1.92

2.22

1.91

3.06 3.01

2.782.71

2.35 2.33 2.36

2.04

0

0.5

1

1.5

2

2.5

3

3.5

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

1903 1918 1939 1948 1960 1970 1975 1980 1990 1995 2000 2007

Popula.onGrowthRat

e

TotalPopula.oninmillio

ns

Popula.onCensusYear

Popula.onSize:Philippines


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Popula.onSize

Theofficialcountofthepopula'onasofthe2007CensusofPopula'onandHousingwas

88,548,366persons


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Popula.onComposi.on

Thepopula'onmaybedescribedusingcertaincharacteris'cswhichmaybephysical,economic,

cultural,social,behavioral,atudinal,or

demographicinnature.

Howcanthepopula/onbedescribed?


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Popula.onComposi.on

Thefigureonthele,

calledapopula.on

pyramid,showsthe

composi'onofthePhilippinepopula'on

byageandsex.

Thisfiguremaybe

usedtodescribeanypopula'onsage-sex

structure.


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Popula.onProcesses

The3majorpopula'onprocessesthatdefinea

popula'onsdemographiccharacteris'csare:

1.Fer'lity2.Mortalityand,3.Migra'on

Letusexamineeachinturn


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Fer/lity

Popula.onProcesses

referstothecapacityofawomanoracoupleto

producechildren,measuredintermsofthe

numberoflivebirths.

Fertility vs. FecundityFer/lityisthecapacitytoproducechildrenwhile

fecundityreferstophysiologicalcapacitytobear

children.Thusawomanwhoisfer/leisfecundbutaninfer/lewomanmaynotnecessarilybeinfecund

(i.e.awomanwhodoesnothavechildrenyetdoes

notmeanshecannotbearachild!)


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Popula.onProcesses

Mortality

referstothecompleteabsenceorthecessa'onoflife.

expressedintermsofthenumberofdeaths(e.g.infantdeaths,neonatalorpost-neonatal,

childdeaths,adultdeaths).

apersonwhowasseeminglylifelessforsomeNmebutwasneverthelessresuscitatedcannotbeconsidereddead

abirthwhichhasshownsomesignoflife(evenforaveryshortNme)cannotbeconsideredborndead

SignsofLife

crying,

twitchingofmuscle

dila'onofthepupil


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Popula.onProcesses

Migra/onthegeographicmovementofanindividualthatinvolves

crossingaterritorialboundarywiththepurposeof

changingpermanentresidence.

Internal

MigraNon

InternaNonal

MigraNon


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Popula.onChange

Thetotalpopula'onsizeofasub-na'onalareamayincreaseor

decreasedependingonthenumberofbirths,deaths,in-migrants

orout-migrants.


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Popula.onBalancingEqua.on

Pungalltheseprocessestogether,wecantalkofasingleequa'onto

summarizetheirrela'onshipswhichdefinethecharacteris'csofthe

popula'on

P2=P1+(B-D)+(IM-OM)aturalIncrease etMigraNon

P2 =thepopula'onatalaterdate

P1 =thepopula'onataearlierdateB =thenumberofbirths

D =isthenumberofdeaths

IM =isin-migra'on(orimmigra'on)OM=isout-migra'on(oremigra'on)


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DemographicMeasures

Ratesmeasurethelikelihoodoftheoccurrenceofapar'cular

eventinapopula'onversusthepopula.onexposedto

theriskofthateventwithinaspecified'me

EXAMPLE:

AGE-SPECIFICFERTILITYRATE

Births15-19-------------------------

Women15-19

Theage-specificfer'lityratemeasuresthenumberofbirthsoccurringamongwomen

ofapar'cularagegroup.

Inthiscase,welookatthebirthsamong

womenaged15-19againstthepopula'on

exposedtotheriskofgivingbirthatthatage(meaning:onlythosewomenaged

15-19!).


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DemographicMeasures

TypesofRatesRatesmaybeclassifiedascrudeorspecific.The

maindifferenceliesinthedenominatorusedto

calculatetherate.

Acruderateiscomputedwhenthereisno

regardtothevaryingexposuretotheevent

ofthepersonsthatcomprisethetotal

popula'oninthedenominator.

(Themenandthosewhoarebeyondtheir

reproducNveagesaresNllcountedhere!)

Specificratesontheotherhand

onlyusesthepopula'onexposed

totheriskofthateventinthe

denominator.

(Everybodyisatriskofdying

regardlessofgender)

CRUDEDEATHRATE

Deaths-------------------------

MidyearPopula'on

CRUDEBIRTHRATE

Births-------------------------

MidyearPopula'on


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DemographicMeasures

MoreonratesCruderatesdividestheeventsbyapopula'on,includingthosewhichare

notnecessarilyexposedtotherisk.

Inourpreviousexample,thecrudebirthratedividesthenumberofbirthsbythe

midyearpopulaNon(whichincludes,themenandthosewhoarebeyondthe

reproducNveages,i.e.thosebelow15orover49)

Specificratesontheotherhand,takesintoaccountvaryingpopula'on

characteris'cs.Weknowfromtheorythatagehasaneffectonthefer'lity

ofwomen(i.e.therewillbemorebirthsamongtheyoungerwomen

comparedtotheold)

Thusinourpreviousexample,weonlyusedthenumberofbirthsbornto

womenaged15-19dividedbythetotalnumberofwomenaged15-19.


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DemographicMeasures

SomeexamplesofRates:

Popula'onGrowthRate

TotalFer'lityRate

Contracep'vePrevalenceRate


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DemographicMeasures

Ra/oWhenonewishestorelateonenumbertoanother

number,ara'ocanbecalculated.

Wemaywanttocomparethenumberofmalesvis--visthenumberoffemalesinaparNcularpopulaNon,

thuswecomputeasexraNo.Wethereforedividethe

numberofmalesagainstthenumberoffemales.The

iniNalanswerisusuallymulNpliedbyaktoenableoneto

interprettheraNomoreeasily.


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DemographicMeasures

Anotherexample:Ifamunicipalityhasatotalpoliceforceof20menandofficers

andthemunicipalityhasatotalpopula'onof10,500persons,

howmanypolicemenarethereforevery1,000persons?

=2,000

20policemen

10,500persons

1,000

Toknowthis,wesimplydivideonegroupoverthe

otherandmulNplybyourdesirednumber:


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DemographicMeasures

Somecommonlyusedra/os:

Canyougiveotherra'oswhichcanbeusefulin

yourownwork?

DoctorstoPopulaNonraNo

HospitalBedstoPopulaNonraNoTextbooktoPupilraNo

TeachertoStudentRaNo


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DemographicMeasures

Propor/on

Tostudytherela'onofonesub-groupinthe

popula'ontothetotalpopula'onitself,apropor'onisused.

Thismeansthatthenumberinthenumeratorisa

memberofthepopula'onusedinthe

denominator.Dividingthesenumberswillgiveyou

apropor'on.


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DemographicMeasures

PercentageWhenthepropor'onisexpressed

asunitsof100,apercentageis

produced.

Accordingtothe2000Census,thenumberofMalesin

thePhilippinesis38,524,266,whilethetotalpopula'on

is76,504,077

CanyoutellwhatproporNonaremalesinthe

Philippinesforthatyear?

WhatpercentageofthePhilippinepopulaNonare

femalesthen?

.5036

49.64%

Heresanexample:


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DemographicMeasures

IfyourememberyourbasicstaNsNcscourses,youforsurehaveencountered

whatarecalledMeasuresofCentralTendency.Theymayalsobeusedfor

compuNngpopulaNonindicators.Theseinclude:

Mean

oraverageexpressestheamountofthecharacteris'coreventpermemberorunit(inthe

denominator)assumingeachmemberorunit

possessesanequalshareofthecharacteris'corevent

(inthenumerator).

Forexample,ifyoudivideyourtotalpopulaNonversusyourtotal

numberofhouseholds,youwillgettheaveragenumberofpersons

perhousehold.


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MedianThemediandividesthepopula'on

intotwoequalgroupsaccordingtothe

characteris'coneislookingat.

DemographicMeasures

Canyougivesomepopula'oncharacteris'cswhere

youcanusethemeanormedianwith?

Forexample,whenonespeaksofamedianage,thiswillmeanthathalf

ofthemembersofthepopulaNonwillbeolderthanthemedianage,

whiletheotherhalfofthepopulaNonisyoungerthanyourmedianage.


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DemographicMeasures

Percentdifference

Thismeasureshowbigonenumberisagainstanother

number.Theirrela'vedifferenceisexpressedasa

percentage,thuscalledpercentdifference.


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Rateofchange

DemographicMeasures

Likeourpreviousexample,therateofchangecomparestwo

valuestogether.Howeverinthiscase,welookathowmuchone

valuehaschanged(increaseordecrease)overtwopointsin

'me.Theincrement(i.e.thedifference)isexpressedinpercentage(overorunder)theothervalue.


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DemographicMeasures

MidyearPopula/on

Themidyearpopula'onreferstothesizeofthepopula'on

ofapar'cularareaasofJuly1oftheyearforwhichthe

rateisbeingcomputed.

Itisanapproxima.onofthepopula.onexposedtothe

riskofapar'cularevent,wheneverthisvalueisnotreadily

available

Thisvaluemaybecalculatedforthetotalpopula'onoror

accordingtospecificcharacteris'csofinterest(e.g.age,

gender,educa'onetc.


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DemographicMeasures

Calcula/ngtheMidyearPopula/on

Themidyearpopula'onisderivedusingtheformula:

P1 =Popula'onintheearliercensus

P2 =Popula'oninthelatercensus

n =numberofmonthsbetweenP1anddesired midyearpopula'ones'mate

N =numberofmonthsbetweenP1andP2


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DemographicMeasures

1990 2000 20071-May 1-May 1-Aug

60,703,206 76,504,077 88,574,614

Theabovetablegivesthetotalpopula'onofthe

Philippinesaccordingto3succeedingcensusyears.

GivenourformulaforcalculaNngthemidyearpopulaNon,canyoucomputeforthemidyearpopulaNonin1995?

Howboutin2005?


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Thank You!

Documents

1- Overview of Demographic Concepts