7/28/2019 Demography~by cHicken AdoBO

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Demography(Lectured by: Dr. Arnel Herrera)

- Demography is the scientific study

* Community Medicine and DemographyCommunity medicine is vitally concerned withpopulation as the health of the people depends upon:1. the number of people2. the space they occupy

3. the skill that they acquire

* Three phenomena in population

~(@) Size of population

- actual umber of the population- basis for many vital statistics- knowing the size of the population is done by

enumeration of all persons in the community, which is

called Census-- done every 5-10 years

*Vital statistics - birth rate and death rate-There are two methods of making census:(a) De facto census: counting individuals wherever they

actually are o the day the census is conducted

-- the people in transit are not counted(b) de jure census: counting individuals at their legalpermanent residence regardless to whether or notthey are physically present at the time of the census-- some individual can be counted twice

*Population density is midyear population divided byland area in square kilometer

*Population is based on the de facto definition ofpopulation, which counts all residents regardless oflegal status or citizenship.

*Land area - countrys total area

94M / 300,000 = 313 persons/sq. km

Population densityWorld (land only) 47 person/sq.km

Macau (China) 18,534 person/sq.kmPhilippines - 313 person/sq.kmThailand - 132 person/sq.kmCanada - 3 person/sq.km

~(@) Composition of the population- studying the composition includes: age and sex

composition, age pyramid, dependency ratio

*Age & Sex composition- proportion of males & females in different age-groups- Direct bearing on social, economic, health need of

communityExample: in aging population, the community shouldarrange health care for elderly

*Sex Ratio- ratio of males to females in the population- sex ratio =number of males X 1000

Number of Females- sex ratio of the Philippines (2011 est.)

At birth: 1050 male/1000 female

15-64 years: 1000 male/1000 female65-over: 760 male/1000 female

Factors:1. Difference in mortality conditions of males & females2. Sex selective abortion and infanticides

* Age Pyramid- pictorial presentation (double histogram) of the age-sex

composition of a population- male & female are compared for age1. Under-developed/developing country:

-- broad base and tapering top

a.k.a Expansive or Expanding population - populationmeans there is low standard of living (poor medicalcare)

2. Developed country: spindle shape (wider in the middle

and the base is narrow)a.k.a. Contractive or Constructing population - there isdecreased birth rate

3. Ellipse or oblong shape - stationary or stable population-- narrow base, low birth rate, low death rate, big

percentage of older people w/c implies a high standardof living

-- these population pyramids helps plan for the next 50years

~(@) Dependency Ratio- the ratio of economically dependent population to

economically independent populationTotal dependency Ratio

= children (65 y/o X 100Working age (15-64 y/o)

~(@) Distribution of the Population

1. Fertility2. Mortality

3. Migration

~(@) Fertility - Is the actual reproductive performance ofa woman or a group of women. A womans

reproductive period is roughly from 15 to 49 years ofage

- Fertility indicators:-- Crude birth - is the simplest indicator of fertility

Live birth X 1000/midyear population-> making annual comparisons-> to detect trends in fertility in a given country-> in comparing different population*Factors:1. Number of females specifically those 15-49 y/o

2. Level of infant and preschool mortality rates3. Socioeconomic level of the country4. Cultural and religious factors

5. Knowledge, attitudes and motives for adoptingor rejecting family planning

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-- General fertility rate

Live births X 1000/midyear female pop (15-49 y/o)*Weakness of GFR1. the marital status2. the differences in fertility levels in various age

groups of reproductive period

-- Age specific fertility rateLive births in specific age group X 1000Midyear population of women in that age group

- the whole reproductive life of females is divided

into seven age groups, each of five years duration(namely 15-19, 20-24, years-- Total fertility rateTFR = 5 X ASFR

1000

Total Fertility rate:- The expected number of births per woman at currentfertility rate

*TFR gives an idea of total family size

- total number of children borne by a women duringher child bearing age (15-49 years)

- TFR in Philippines: 3.19 (2011 est.) 6.5 (1968)- Family size depends upon:1. duration of marriage

2. education of couple3. number of live births4. number of living children5. preference to male

* Reasons for High Birth Rate in Philippines1. early marriage2. low standard of living

3. religion 80% catholic4. absence of family planning habit

Net Production Rage (NRR)The rate of replacement of females in the population per

generation

= number of girls born and survivedNumber of the women survived after the end of

reproductive(all female age >50)

If NRR is >1, the reproductive performance of thecommunity is below

~(@) Mortality Indicator- crude death rate

= The total number of deaths in a year x 1000

Midyear population in the same year

~(@) Migration- is the change of residence of a person or group of

persons for better life and higher standard of living

1. Internal migration is the movement within the

boundaries of given countrya. Rural-Urban migrationb. movement of nomads

2. External migrationa. permanent migrationb. Temporary migration

*The role of migration role is minimal when compared tofertility and mortality.

POPULATION GROWTH

The population grows according to two factors: birth rateand death rate. The difference between these two iscalled the rate of natural increase.

The rate of natural increase is expressed as a percent.Rate of natural increase (RNI) = CBR-CDR

10The growth rate takes into consideration: birth, death &

migrationGrowth rate = RNI + Net migration rate

Net migration rate = Immigrants - Emigrants

LIFE EXPENTANCY

- expectation of life at a given age is the average numberof years which a person of that age may expect to live,according to the mortality pattern prevalent at thatage

- Indicator of country development & overall health- Expectation of life at birth

*Reasons for increase life expectancy

1. Mass control of disease2. Advance in medical science

2. better health facility4. impact of national programs6. improvements on food supply6. international aid

7. Development of social conciseness among masses

*Age of Marriage -great impact on fertility

*Nutrition- well fed society - low fertility- high fed society - high fertility

* Family Planning - most practice: oral contraceptives

* Education - inversely proportional to fertility

* Economic status- inversely proportional to fertility

- Economic development is the best contraceptive

* Implications of Population Explosion

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1. Economic implications

2. Demographic Implications3. Environmental / Ecological implications4. Social / Political implications

~(@) Demographic Transition ModelStage 1. Birth rates are high because:

- no birth control or family planning- high infant mortality rate so parents produce more inhope that several will survive- many children needed to work in agriculture- children expected to support parents in later life in

the absence of pensions- children regarded as sign of virility and status insome societies- Religious beliefs - Roman Catholic

* Death rates are high because- lack of access to medical science/supplies - fewdoctors, hospitals, drugs- Poor hygiene

- Famine- Diseases

-- Natural increase (population growth) is low becausealthough there are a lot of births the similarity high

number of deaths effectively cancels them out

Stage 2: Urbanizing / Industrializing- Birth rates- Death rates begin to fall because:

- Improved medical care (GOBI, Immunization)

- Improved sanitation and water supply systems

reduces disease- Improvements in agricultural efficiency - Improvedcommunication

-- Natural increase (population growth) is high becausethere is now a large gap between births and deaths,increasing the population rapidly.

Stage 3: Matured Industrial- Birth rates begin to fall because:

- lower infant mortality rate means less pressure to

have many children- widespread availability and knowledge of planning- change from agrarian to mechanization leads to a

reduction in workforce requirement- welfare system pension- Emancipation of women and improved educationalopportunities

- large families increasingly viewed as economic andsocial burden

- increased desire to pursue material lifestyles

-- Remains high due to the gap between births anddeaths

Stage 4: Post Industrial- Death rates remain low because:

- continued advances in pediatric care further reduce

infant mortality rates- Improved diets- Continued advances in geriatric care increase lifeexpectancy

- Increase in preventative health care- enhanced public services for elderly

- universal state pension scheme

-- Natural increase (population growth) is again low asbirths and deaths virtually cancel each other out butthe population is high

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