CPH-Lab-Demography.pdf

CPH Laboratory – Demography De Facto Method Demography Is done when the people are assigned to the place where they are physically present at Is the statistical study...

CPH Laboratory – Demography De Facto Method Demography Is done when the people are assigned to the place where they are physically present at Is the statistical study of human population. the time of the census regardless of their It can be a very general science that can be usual place of residence. applied to any kind of dynamic human population, that is, one that changes over Where will you go in case of error in Birth time or space. Certificate? It encompasses the study of the size, The keeper of the birth and death record in structure and distribution of these the Philippines? populations, and spatial and/or temporal Since the census asks for a complete changes in them in response to birth, enumeration of the population, it is usually a migration, aging, and death. very expensive undertaking. Census It will require money to pool together people and other resources to complete the census A census is the other common direct in a limited period of time. method of collecting demographic data. Instead of a census, demographic A census is usually conducted by a national information can still be collected from a government and attempts to enumerate sample of given population. This is called a every person in a country. However, in sample survey. Even if the obtained data contrast to vital statistics data, which are come from a small number of people typically collected continuously and proportionate to the total population, the summarized on an annual basis, censuses results will always be generalized for the typically occur only every 10 years or so, and whole population. thus are not usually the best source of data Registration systems such that collected by on births and deaths. the civil registrar’s office deal with recording Analyses are conducted after a census to vital events in the community. Vital events estimate how much over or undercounting refer to births, deaths, marriage, divorces took place. and the like. Census is defined as an official and periodic Censuses do more than just count people. enumeration of population. During the They typically collect information about census, demographic, economic and families or households, as well as ab0ut such social data are collected from a specified individual characteristics as ego, sex, population group. These data are late marital status, literacy/education, collected collated, synthesized and made employment status and occupation, known to the public for purpose of and geographical location. determining and made known to the public They may also collect data on migration (or for purpose of determining and explaining place of birth or of previous residence), trends in terms of population changes and language, religion, nationality (or ethnicity planning programs and services. or race), and citizenship. In countries in De Jure Method which the vital registration system may be incomplete, the censuses are also used as a Is done when people are assigned to the direct source of information about fertility places where they usually live regardless of and mortality; where they are at the time of census. There are two methods of data collection: individual at a given age could expect to live at present mortality levels. Direct and indirect The total fertility rate, the number of live Direct Data births per woman completing her reproductive life, if her childbearing at each Come from vital statistics registries that age reflected current age-specific fertility track all births and deaths as well as certain rates. changes in legal status such as marriage, The replacement level fertility, the divorce, and migration (registration of place average number of children a woman must of residence). In developed countries with have in order to replace herself with a good registration systems (such as the daughter in the next generation. For United States and much of Europe), registry example, the replacement level fertility in statistics are the best method for estimating the US is 2.11. This means that 100 women the number of births and deaths. will bear 211 children, 103 of which will be Indirect Methods females. About 3% of the alive female infants are expected to decrease before they bear Of collecting data are required in countries children, thus producing 100 women in the where full data are not available, such as is next generation. the case in much of the developing world. The gross reproduction rate, the number One of these techniques is the sister method, of daughters who would be born to a woman where survey researchers ask women how completing her reproductive life at current many of their sisters have died or had age-specific fertility rates. children and at what age. With these surveys, The net reproduction ratio is the researchers can then indirectly estimate expected number of daughters, per newborn birth or death rates for the entire population. prospective mother, who may or may not Other indirect methods include asking survive to and through the ages of people about siblings, parents, and children. childbearing. The crude birth rate, the annual number A stable population, one that has had of live births per 1,000 people. constant crude birth and death rates for such The general fertility rate, the annual long time that the percentage of people in number of live births per 1,000 women of every age class remains constant, or childbearing age (often taken to be from 15 equivalently, the population pyramid has an to 49 years old, but sometimes from 15 to unchanging structure. 44). A stationary population, one that is both Age-specific fertility rates, the annual stable and unchanging in size (the difference number of live births per 1,000 women in between crude birth rate and crude death particular age groups (usually age 15-19, 20- rate is zero). 24 etc.) A stable population does not necessarily The crude death rate, the annual number remain fixed in size, it can be expanding or of deaths per 1,000 people. shrinking. The infant mortality rate, the annual number of deaths of children less than 1 year Note that the crude death rate as defined old per 1,000 live births. above and applied to a whole population can The expectation of life (or life give a misleading impression. For example, expectancy), the number of years which an the number of deaths per 1,000 people can be higher for developed nations than in less-  developed countries, despite standards of Some are infecund due to disease or genetic health being better in developed countries. dysfunction. This is because developed countries have Mothers could be infecund when they proportionally more older people, who are breastfeed. more likely to die in a given year, so that the For individual fecundity ranges between 0- overall mortality rate can be higher even if 30 children. the mortality rate at any age is lower. The fertility rates can also give a misleading Factors accounting for fertility impression that a population is growing fecundity gaps faster than it in fact is, because measurement Cultural values of fertility rates only involves the Social roles reproductive rate of women, and does not Economic adjust for the sex ratio. For example, if a Health population has a total fertility rate of 4.0 but the sex ratio is 66/34 (twice as many men as Intermediate factors affecting fertility women), this population is actually growing Fecundity: at a slower natural increase rate than would a population having a fertility rate of 3.0 and Ability to have intercourse a sex ratio of 50/50. This distortion is Ability to conceive greatest in India and Myanmar, and is Ability to carry pregnancy to term present in China as well. Sexual unions: % of women in union. Public workers determine the population This rate is affected by other demographic size not because she simply wants to know factors such as: The formation and dissolution how large or small the population is. of unions (marriage, divorce, Etc.) Knowing the population size of a place Age at first marriage allows the PHW to make comparisons about population changes over time. Time spent outside the union… etc. It also helps her rationalize the types of Male mortality levels health programs or intervention which are going to be provided for the community. Intermediate factors affecting fertility Birth Control: Populations can change through three processes: Use of contraceptives A. Fertility (births) Contraceptive sterilization B. Mortality (deaths) Induced abortion C. Migration B. Mortality is the study of the causes, A. Fertility involves the number of children consequences, and measurement of that women have and is to be contrasted with processes affecting death to members of the fecundity (a woman’s childbearing population. potential). C. Migration refers to the movement of persons from an origin place to a destination FECUNDITY place across some pre-defined, political The physiological ability of individuals or boundary. couples to have children.  Migration researchers do not designate 1. Absolute increase per year – measures movements ‘migrations’ unless they are the number of people that are added to the somewhat permanent. population per year. This is computed using Thus, demographers do not consider tourists the following formula: and travelers to be migrating. While demographers who study migration typically do so through census data on place of residence, indirect sources of data including tax forms and labor force surveys are also important. One method of measuring the population 2. Relative increase – is the actual difference size is by determining the increase in the between the two census counts expressed in population resulting from excess of births percent relative to the population size made compared to deaths. during an earlier census. 1. Natural increase is simply the difference between the number of births and the number of deaths occurring in a population in a specified period of time. Population Composition The composition of the population is 2. Rate of Natural increase is the difference commonly described in terms of its age and between the Crude Birth Rate and the Crude sex. The PHW utilizes data on age and sex Death rate occurring in a population in a composition to decide who among the specified period of time. population groups merits attention in terms of health services and programs. 1. Sex composition – to describe the sex composition of the population, the nurse computes for the sex ratio. The sex ratio compares the number of males to the number of females in the population using The crude birth rate, the annual number the formula below. of live births per 1,000 people. The crude death rate, the annual number of deaths per 1,000 people. The second method of measuring population size is to determine the increase in the population using data obtained during two census periods. This implies that the 2. Age composition increase in the size of the population is not merely attributed to excess in births but also There are two ways to describe the age the effect of migration. These are: composition of the population. A. Median age divides the population into two equal parts. So, if the median age is said to be 19 years old, it means half of the population belongs to 19 years and above, while the other half belongs to ages below 19 years old. B. Dependency ratio compares the number of economically dependent with the economically productive group in the population. The economically dependent are those who belong to the 0-14 and 65 above age groups. Considered to be economically productive are those within the 15-64 age group. The dependency ratio represents the number of economically dependent for every 100 economically productive.