4TH YEAR COMMED Demography & Vital Indices

8/3/2019 4TH YEAR COMMED Demography & Vital Indices

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Definitiony Demography :

to describe population characteristics, size or number,

geographical distribution & to study the change ofthese determinants over time.

y Rate :

the frequency of an event in a population in relation totime.


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y Ratio :

the occurrence of an event in relation to other event.

y Proportion :

ratio that compares a part in a whole.

y Index :is used when true denominator is difficult to becalculated so a related accurate denominator is usedinstead


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Population censusTo enumerate people at a certain area at certain time. Itcollects various data* every 10 year. Mid year population is thenumber of population calculated from census at the 1st of

July(standard)

Importance of census :yCalculate the actual number of populationyPlanning for future health program

yProvide general characteristics to compare with othercountry.

yTo estimate the population in years between censuses.yCalculate vital statistical rates


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Drawback of census :y Expensive, time consuming, personnel

y If it consumes a prolonged time in data collection andanalysis so the data will be irrelevant.

y Data is inaccurate (people cheat)y Problems of nomad people

y Lack of cooperation from people or data collectors

y Data collectors may fill the questionnaire himself if

houses are empty.


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Inter-census estimation

1) Arithmetic method

2) Rate of natural increases

3) Total growth rate

4) Graphic method

5) Geometric method

RNI = birth rate death rate

TGR = (birth rate + immigration) (death rate + emigration)

Adv : assumes the populationgrowth is not linear for each year


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Population growth patterns

Birth Death RNI Lifeexpectancy

Example

Highpotential

high high > 2.5% short Pakistan

Transitional high decreasing 1.5 2.5% moderate Egypt

Stationary low low < 1.5% high Sweden


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Life expectancy :The average number of years that can be expected to belived by any individual at certain age. LE is directlyproportional to:

yCountry development

ySocio-economic level

yHealth service standard

y

Use of new technologyyLiteracy

yGood nutrition

yHealth environment


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Population pyramidy Characteristics of population pyramid

i. Base of the pyramid represents the birth rate.

ii.H

eight represents the number of years to be lived at specificage(L.E.)

iii. Top represents the percentage of old age group.

iv. Slope of the pyramid represents the age specific death rates.

v. Percentage of males and females at each age group.

vi. Dependency ratio : is the number of young ages below 15yrs old + number of old ages over 65 (who are dependent)per 100 person from 15 65 (who are independent)


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y

Different profiles of population pyramids :Base Tapering

(slope)

Expansivemodel Wide Rapid

Rapid populationgrowth and high

birth rate

Constrictive

modelNarrow Slow

Low birth rate anddecreased death

rate

Stationarymodel

Narrow Very slowLow birth rate and

low death rate


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Vital indices

I. General fertility rate

II. Age specific fertility rate

CBR = number of live birth/mid year

population x1000

GFR = number of live birth /total women

in reproductive age 15-49yrs x1000

ASFR = number of live birth born tomothers from 15-20yrs / total women in

reproductive age 15-20yrs x1000

Fertility indices

C

rude birth rate


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V. Total fertility rate

VI. Fecundity rate

VII. Gross reproduction rate

VIII. Net reproduction rate

Number of live birth / number of married woman x1000

GRR = TFRx born female/ Woman in childbearing period x1000

NRR = GRRx LE of females during childbearing period

Total number of all seven intervals for ASFR


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I. Incidence rate

II. Prevalence rateI. Point

II. Period

Morbidity indices

Number of new cases of illness / total population x1000

Number of current cases of illness at point of time/ totalpopulation at point of time x1000

Number of current cases of illness over a period of time/total population at mid year of the same period x1000


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III. Attack rate

IV. Fatality rate

Number of new cases of sp. disease during epidemicoutbreak / total number of persons at risk x1000

Number of new death of sp. disease / number of cases of

that diseasex

1000


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I. Crude death rate

II. Age specific mortality rate

Death indices

Number of death / mid year populationx

1000

Number of death in a specified age group and time /

Population of the same age group and time x1000


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III. Age-sex specific mortality rate

IV. Cause specific mortality rate

III. Proportional(relative) mortality rate

Number of death in a specified age and sex group /

Population of the same age and sex group x1000

Number of death from a sp cause at certain time /

Population of the same period time x1000

Number of death in a specified age group and time /

Total death of all causes x1000


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Sources of datacollection

Primary

Qualitative data

In-depthinterview

Focus group

Quantitativedata

Survey

Secondary

-records

-surveillance-census

Sources of data collection

4TH YEAR COMMED Demography & Vital Indices

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