3 Materials and methods in Demography

Atreyo Mondal and Gautam Kshatriya

epgp books

 

 

 

Contents

 

1.  Introduction

2.  Subfields of Demography

3.  Why Study Population

4.  Demographic analysis

4.1. Primary Demographic Data and Statistics

4.2. Secondary Sources

4.2.1 Data sources

4.2.1.1. Main Source

4.2.1.1.1. Census

4.2.1.1.2. Vital Statistics

4.2.1.1.3. Sample Survey and Censuses and Surveys

4.2.1.1.4. Statistics Produced from Combinations of Census and Registration Data

4.2.1.2. Some other Source

4.2.1.2.1 Population Registrar

4.2.1.2.2. Demographic Surveillance System (DSS)

4.2.1.2.3. Miscellaneous Sources of Data

5. Summary

 

Learning Objectives

  • To know about different subfields of demography
  • To know about the demographic analysis
  • To know about the demographic data and statistics

    1.  Introduction

 

Demography is the scientific study of human population, including its size, distribution, composition, and the factors that determine changes in its size, distribution, and composition. From this definition we can say that demography focuses on five aspects of human population: (1) size, (2) distribution, (3) composition, (4) population dynamics, and (5) socioeconomic determinants and consequences of population change.

 

Population size is simply the number of persons in a given area at a given time. Population distribution refers to the way the population is dispersed in geographic space at a given time. Population composition refers to the numbers of person in sex, age, and other “demographic” categories. The scope of the “demographic” categories appropriate for demographic study is subject to debate. All demographers would agree that age, sex, race, year of birth, and place of birth are demographic characteristics. These are all characteristics that do not essentially change in the lifetime of the individual, or change in a perfectly predictable way. They are so-called ascribed characteristics.

 

There are many other characteristics also are recognized as within the purview of the demographer. These fall into a long list of social and economic characteristics, including nativity, ethnicity, ancestry, religion, citizenship, marital status, household characteristics, living arrangements, educational level, school enrolment, labour force status, income, and wealth. Most of these characteristics can change in the lifetime of the individual. They are so-called achieved characteristics. Some would include as demography all the areas about which questions are asked in the decennial population census.

 

The study of the interrelationship of these factors with defines the subfield of the formal demography. Beyond these demographic factors of change, there are a host of social and economic characteristics that represent causes and consequences of change in the basic demographic characteristics and the basic components of change. Study of these topics defines the subfields of social and economic demography. It should be evident that the boundaries of demography are not strictly defined and the field overlaps greatly with other disciplines.

 

There has been an expansion of the applications of demography in public health, local government planning, business and human resources planning, environmental issues, and traffic management. This expansion has helped to define the field of applied demography. (Swanson, J., 2004)

 

2. Subfields of Demography

 

The subfields of demography can be classified in several ways. One is in terms of the subject matter, geographic area, or methodological specialty of the demographer—for example, fertility, mortality, internal migration, state and local demography, Canada, Latin America, demography of aging, mathematical demography, economic demography, historical demography, and so on. All these specialties overlap and intersect in many ways. Another classification produces a simple dichotomy, but its two classes are also only ideal typical constructs with fuzzy edges: basic demography and applied demography. The primary focus of basic demography is on theoretical and empirical questions of interest to other demographers. The primary focus of applied demography is on practical questions of interest to parties outside the field of demography (Swanson, Burch, and Tedrow, 1996). Basic demography can be practiced from either the perspective of formal demography or that of socioeconomic demography. The first has close ties to the statistical and mathematical sciences, and the latter has close ties to the social sciences. The key feature of basic demography that distinguishes it from applied demography is that its problems are generated internally. That is, they are defined by theory and the empirical and research traditions of the field itself. An important implication is that the audience for basic demography is composed largely of demographers themselves (Swanson et al., 1996). On the other hand, applied demography serves the interests of business or government administration (Siegel, 2002). Units in government or business or other organizations need demographic analysis to assist them in making informed decisions. Applied demographers conceive of problems from a statistical point of view, investing only the time and resources necessary to produce a good decision or outcome. Moreover, as noted by Morrison (2002), applied demographers tend to arm themselves with demographic knowledge and draw on whatever data may be available to address tangible problems. However, it also is important to note that basic demographers and applied demographers share a common basic training in the concepts, methods, and materials of demography, so that they are able to communicate with one another without difficulty in spite of their difference in orientation.

 

3. Why Study Population

 

Demography can play a number of roles and serve several distinct purposes. The most fundamental is to describe changes in population size, distribution, and composition as a guide for decision making. This is done by obtaining counts of persons from, for example, censuses, the files of continuous population registers, administrative records, or sample surveys. Counts of births and deaths can be obtained from vital registration systems or from continuous population registers. Similarly, immigration and emigration data can be obtained from immigration registration systems or from continuous population registers. Although individual events may be unpredictable, clear patterns emerge when the records of individual events are combined. As is true in many other scientific fields, demographers make use of these patterns in studying population trends, developing theories of population change, and analyzing the causes and consequences of population trends. Various demographic measures such as ratios, percentages, rates, and averages may be derived from them. The resulting demographic data can then be used to describe the distribution of the population in space, its degree of concentration or dispersion, the fluctuations in its rate of growth, and its movements from one area to another.

Source: https://www.slideshare.net/sacibgeography/why-study-population

 

Demographic data play a role similar to that of data in other scientific fields, in that they can be used both for basic and applied purposes. However, demography enjoys two strong advantages over many other fields. First, the momentum of population processes links the present with the past and the future in clear and measurable ways. Second, in many parts of the world, these processes have been recorded with reasonable accuracy for many generations, even for centuries in some cases.

 

While the “demographic perspective” is largely a way of dealing with data, it is present when we (1) bring into play essentially demographic phenomena, such as population size, change in population numbers, numbers of births, deaths, and migration, and age/sex/race composition; (2) apply essentially demographic methods or tools, such as sex ratios, birth rates, probabilities of dying, and interstate migration rates, and their elaboration in the form of model tables, such as life tables, multistate tables, and model tables of fertility or marriage; (3) seek to measure and analyze how these demographic phenomena relate to one another and change over time, such as by cohort analysis or by analyzing the age-period-cohort interaction; and (4) construct broad theories as to the historical linkage or sequence of demographic phenomena, such as the theory of the demographic transition or theories accounting for internal migration flows. In these terms, the demographic perspective can be applied widely to serve a broad spectrum of applied disciplines as well as aid in interpreting broad historical movements. To a large degree, this knowledge is captured in the demographic perspective. It provides demographers with a framework within which data, models, and theory can be used to explain how populations work. As such, the perspective can contribute to the development of both models and theory, which. The demographic perspective also aids in helping us to understand the implications of how populations work. That is, it furthers the aims of demography in its applied sense, not just its basic sense (Swanson et al., 1996). As such, the demographic perspective is important to the further development of demography as an aid to practical decision making (Kintner and Swanson, 1994).

 

4. Demographic analysis

 

Demographic analysis focuses collectively on studying changes in its size, growth rates, and composition.

 

Emphasis is on understanding aggregate processes, but demography is also attentive to the implications of those processes for individuals

 

Source: https://www.slideshare.net/naresh911/market-analysis-of-consumer

 

Many of the indexes used in demography (life expectancy at birth, total fertility rate) translate aggregate-level processes into statements about the demographic circumstances faced by an average or randomly-chosen individual.

 

To understand and analyze the topics and issues of demography, one must have access to appropriate statistics. The availability of demographic statistics has increased dramatically since the 1970s as a result of improved and expanded collection techniques, vast improvements in computing power, and the growth of the Internet.

 

Demographic statistics may be viewed as falling into two main categories: primary and secondary. Primary statistics are those that are the responsibility of the analyst and have been generated for a very specific purpose. The generation of primary statistics is usually very expensive and time consuming. The advantages of primary data are that they are timely and may be created to meet very specific data needs. Secondary statistics differ in that they result from further analysis of statistics that have already been obtained. These are regarded as data disseminated via published reports, the Internet, worksheets, and professional papers. These data may be disseminated freely, as is the case with public records, or for a charge, as with data clearinghouses. Their benefit is that they generally save a great deal of time and cost. The drawback is that data are usually collected with a specific purpose in mind—sometimes creating bias. Additionally, secondary data are, by definition, old data (Stewart and Kamins, 1993).

 

4.1. Primary Demographic Data and Statistics

 

Primary demographic data are most commonly gathered or aggregated at the national level. A country may have a central statistical office, or there may be separate agencies that take the census and compile the vital statistics. Even when both kinds of statistics emanate from the same agency, they are usually published in separate reports, reflecting the fact that censuses are customarily taken decennially or quinquennially and vital statistics are compiled annually or monthly. In some countries, subnational areas such as provinces or states may have important responsibilities in conducting a census or operating a registration system. Data gathered by these regions may be for the sole use of the regions, or they may be gathered for a central national office. The central office may play a range of roles in the analysis and reporting of regional statistics, from simply collecting and reporting statistics that were tabulated in the provincial offices, to collecting the original records or abstracts and making its own tabulations. In either situation, both national and provincial offices may publish their own reports and tabulations. Statistics from different governmental sources may vary with respect to their arrangement, detail, and choice of derived figures. Moreover, what purport to be comparable statistics may differ because of variations in classification or editing rules, varying definitions, or because of processing errors. Demographic data may be collected either through censuses and surveys or through a population register. A population register in its complete form is a national system of continuous population accounting involving the recording of vital events and migrations as they occur in local communities. The purpose of the census or survey is simply to produce demographic statistics. The registration of vital events and population registers, on the other hand, may be at least as much directed toward the legal and administrative uses of its records. In fact, the compilation and publication of statistics from a population register may be rather minimal, partly because these activities tend to disturb the day-to-day operation of the register. Even though the equivalent of census statistics could be compiled from a population register, the countries with registers still find it necessary to conduct censuses through the usual method of enumerating all households simultaneously. This partial duplication of data gathering is justified as a means of making sure that the register is working properly and of including additional items (characteristics) beyond those recorded in the register. There are often restrictions imposed on the public’s access to the individual census or registration records in order to protect the privacy and interests of the persons concerned and to encourage complete and truthful reporting.

 

4.2. Secondary Sources

 

Secondary sources may be either official or unofficial and include a wide variety of textbooks, yearbooks, periodical journals, research reports, gazetteers, and atlases. In this section, only a few of the major sources of population statistics are mentioned. These statistics address the population and its components, as well as demographic aspects that can affect these elements, such as health and migration statistics.

 

4.2.1. Data sources

 

4.2.1.1. Main sources

  • Census
  • Vital registration
  • Sample surveys

    4.2.1.1.1. Census

 

“The total process of collecting, compiling, evaluating, analysing, and publishing or otherwise disseminating demographic, economic and social data pertaining to all persons in a country or in a well delineated part of a country at a specified time.” (United Nations 2008), total process not sufficient to simply collect and collate information in a census, but also analyzes, publish and disseminate the data. Demographic, economic and social data to collect more than just a simple headcount of the population universality to enumerate all people in a population Simultaneity to produce a snapshot of the population at a point in time

 

The oldest, most demanding, and most important source of demographic information many demographic methods developed for census data among the most complex and massive peacetime exercises a nation undertakes. Requires the mapping the entire country, mobilizing and training an army of enumerators, conducting a massive public campaign, canvassing all households, collecting individual information, compiling vast amounts of completed questionnaires, and analysing and disseminating the data

 

4.2.1.1.2. Vital Statistics

 

Vital statistics is the second main source for demographers. Collect information on individuals when (or shortly) after they experience the vital events (birth, marriage, death, (sometimes) migration). In almost all developed countries, registration of births, deaths, and marriages is compulsory. International View According to the United Nations’ Handbook of Vital Statistics Methods, “a vital statistics system can be defined as including the legal registration, statistical recording and reporting of the occurrence of, and the collection, compilation, analysis, presentation, and distribution of statistics pertaining to ‘vital events’, which in turn include live births, deaths, foetal deaths, marriages, divorces, adoptions, legitimations, recognitions, annulments, and legal separations” (United Nations, 1985). The end products of the system that are used by demographers are, of course, the vital statistics and not the legal issues of the document.

 

For example, only 60% of the 230 countries and areas register at least 90% of births occurred in the country. While for death registration, only 47% of the countries and areas have at least 90% coverage. (UNSD 2012).

 

Events Registered As suggested earlier, events registered may include live births, deaths, fetal deaths (stillbirths), marriages, divorces, adoptions, legitimations, recognitions, and legal separations. Not all countries with a civil registration system register all these types of events or publish statistics on their numbers. Moreover, some types are of marginal interest to demographers. As is pointed out in the United Nations Handbook, other demographic events, such as migration and naturalization, are not generally considered part of the vital statistics system because they are not usually recorded by civil registration (United Nations, 1985). Moreover, these events are not considered “vital” events.

 

4.2.1.1.3. Sample Survey and Censuses and Surveys

 

Collect vital statistics where the official registration system is inadequate or nonexistent and for intercensal period. Collect supplementary demographic and other data, where it is not feasible to collect the same from the population census. Since the 1970s, coordinated demographic surveys have been taken around the world through the World Fertility Survey (WFS), the Demographic and Health Surveys (DHS), the Multiple Indicator Cluster Surveys (MICS), or other national types of survey. Sampling method is one of the important methods for the collection of population data. Census operations at national level being costly affair are conducted once in a decade, but in between many happenings necessitate collection of information on different aspects of population. In some areas it is not possible to have counting at the time of census, whereas in many other cases it may be found that collection of data was erroneous. In order to deal with these problems and come over difficulties sample surveys are organised. In every country this type of survey is always carried eighter in one form or the other. In some countries there is also the system of National Surveys. Such a survey can be Random Sampling or Stratified Random Sampling. For a good sample it is essential that it should be independent and available. It should not have any bias, if unbiased and dependable results are desired to be collected. Whether it is random sampling or stratified random sampling it is essential that the system should be very carefully picked up and used.

 

The advantages of this sampling survey is mostly not a costly method and nation can afford it, if needed be, the number of people who engage is much less as compared with census, information on population aspects as abortions, contraception study of fertility which cannot be collected during the census can be collected with the sampling method thus the quality of data collected through this method is better than census. This type of survey is becoming popular with the planners and administrators because of their reliability.

 

The distinction between a population census and a population survey is far from clear-cut. At one extreme, a complete national canvass of the population would always be recognized as a census. At the other extreme, a canvass of selected households in a village to describe their living conditions would probably be regarded as a social survey. But neither the mere use of sampling nor the size of the geographic area provides a universally recognized criterion. Most national censuses do aim at a complete count or listing of the inhabitants. Sampling is also used at one or more stages for purposes of efficiently collecting detailed characteristics of the entire population. The main objective of a population census is the determination of the number of inhabitants.

 

The definition used by the United Nations is as follows: “A census of population may be defined as the total process of collecting, compiling, evaluating, analyzing and publishing or otherwise disseminating demographic, economic and social data pertaining, at a specified time, to all persons in a country or delimited part of a country” (United Nations 1998).

 

In many modern population censuses, numerous questions are also asked about social and economic characteristics as well. A survey, on the other hand, is a collection of standardized information from a specific population, or a sample from one, usually but not necessarily by means of questionnaire or interview (Robson, 1993). The main purpose of a survey is to produce statistics about some aspects or characteristics of a study population (Fowler, 1993). The field of surveys uses a unique perspective on approach, methods, errors, analysis, and conclusions.

 

The line between census and survey is further blurred by the concept of error. A census that failed to enumerate 100% of the population and its characteristics is, by definition, an incomplete census.

 

The typical scope of a census or demographic survey is the size, distribution, and characteristics of the population. In countries without adequate registration of vital events, however, a population census or survey may include questions about births or deaths of household members in the period (usually the year) preceding the census. Moreover, even when vital statistics of good quality exist, the census or survey may include questions on fertility (e.g., children ever born, children still living, date of birth of each child) because the distribution of women by number of children ever born and by interval between successive births cannot be discovered from birth certificates. Of special interest are the periodic national sample surveys of households that have been established in a number of countries. These may be conducted monthly, quarterly, or only annually. In some countries, they have been discontinued after one or two rounds because of financial or other problems. Usually the focus of these surveys is on employment status, housing and household characteristics, or consumer expenditures attributable to certain limited demographic characteristics, rather than the demographic information itself. Both censuses and surveys have also tended to grow in the range of topics covered, in sophistication of procedures, in accuracy of results, and in the volume of statistics made available to the public.

 

4.2.1.1.4. Statistics Produced from Combinations of Census and Registration Data

 

Some examples of data and measures based on combinations of population figures from a census with vital statistics were given earlier. Rates or ratios that have a vital event as the numerator and a population as the denominator are the most obvious type. The denominator may be a subpopulation, such as the number of men 65-to-69-years old (e.g., divided into the number of deaths occurring at that age) or the number of women 15-to-44-years old (e.g. divided into the total number of births). Moreover, the population may come from a sample survey or a population estimate, which in turn was based partly on past births and deaths. Products of more complex combinations include current population estimates, life tables, net reproduction rates, estimates of net intercensal migration, and estimates of relative completeness of enumeration in successive censuses. The computation of population projections by the so-called component method starts with a population disaggregated by age and sex, mortality rates by age and sex, and fertility rates by age of mother. There may be a series of successive computations in which population and vital statistics are introduced at one or more stages. All of these illustrative measures can be produced by the combination of statistics. A different approach is to relate the individual records. This is the approach taken in matching studies. By matching birth certificates, infant death certificates, and records of babies born in the corresponding period of time in the census, one can estimate both the proportion of births that were not registered and the proportion of infants who were not counted in the census. Other statistics of demographic value can be obtained by combining the information from the two sources for matched cases in order to obtain a greater number of characteristics for use in the computation of specific vital rates. For example, if educational attainment is recorded on the census schedule but is not called for on the death certificate, a matching study can yield mortality statistics for persons with various levels of educational attainment. When the same characteristic, such as age, is called for on both documents, the matching studies yield measures of the consistency of reporting. In a country with a population register, matching studies with the census also can be carried out. Again, the resulting statistics could be either of the evaluative type or could produce cross-classifications of the population based on a greater number of characteristics than is possible from either source alone.

 

4.2.1.2. Some other Source

  • Population Registrar   
  • Demographic Surveillance System (DSS)
  • Miscellaneous Sources of Data

   4.2.1.2.1 Population Registrar

 

A registration system is the other common method for collecting demographic data. It differs from a census in that the registration system is conducted for both administrative and statistical uses and in other ways. For present purposes, a population registration system can be defined as “an individualized data system, that is, a mechanism of continuous recording, and/or of coordinated linkage, of selected information pertaining to each member of the resident population of a country in such a way to provide the possibility of determining up-to-date information concerning the size and characteristics of that population at selected time intervals.” (United Nations, 1969).

 

Definitions of the universal register, partial register, and vital statistics registration differ somewhat, but it is understood that the organization, as well as the operation, of all are made official by having a legal basis. It must be noted also that the content, consistency, and completeness of population registration systems vary not only by country, but over time and within countries as well. Events such as war, famine, or even unusual prosperity that might last for short or long periods of time may create an impetus for greater or less registration or the linkage or destruction of existing records.

 

4.2.1.2.2. Demographic Surveillance System (DSS)

 

DSS monitors demographic and health characteristics of a population living in a well-defined geographic area. A baseline census is followed by regular update of key demographic events (birth, death, migration, marriage…) and heath events.

 

4.2.1.2.3. Miscellaneous Sources of Data

 

Some of the partial official registers that are less widely used for demographic studies, registers or other records maintained by private agencies, records that apply directly to things but indirectly to people, and the like. Again, statistics from these sources are sometimes used for population estimates. They include the following:

  • Tax office records of taxpayers and their dependents City directories (addresses of householders published by private companies)
  • Church membership records Postal delivery stops
  • Permits for new residential construction and for demolition
  • Utility records Personal property registration and special licensing.

    5.  Summary

 

Demography is the scientific study of human population, including its size, distribution, composition, and the factors that determine changes in its size, distribution, and composition. Population size is simply the number of persons in a given area at a given time. Population distribution refers to the way the population is dispersed in geographic space at a given time. Population composition refers to the numbers of person in sex, age, and other “demographic” categories. Demographic data play a role similar to that of data in other scientific fields, in that they can be used both for basic and applied purposes. However, demography enjoys two strong advantages over many other fields. First, the momentum of population processes links the present with the past and the future in clear and measurable ways. Second, in many parts of the world, these processes have been recorded with reasonable accuracy for many generations, even for centuries in some cases. Demographic analysis focuses collectively on studying changes in its size, growth rates, and composition. Demographic analysis focuses collectively on studying changes in its size, growth rates, and composition.

 

To understand and analyze the topics and issues of demography, one must have access to appropriate statistics. Demographic statistics may be viewed as falling into two main categories: primary and secondary.

 

Primary demographic data are most commonly gathered or aggregated at the national level. A country may have a central statistical office, or there may be separate agencies that take the census and compile the vital statistics. Secondary sources may be either official or unofficial and include a wide variety of textbooks, yearbooks, periodical journals, research reports, gazetteers, and atlases.

 

Besides the primary and secondary sources some other sources are population registrar, demographic surveillance system (DSS), miscellaneous sources of data.

you can view video on Materials and methods in Demography

    References

  1. Fowler, F. J., (   1993). Survey Research Methods. Newbury Park, CA: Sage Press.
  2. Kintner, H., & Swanson. D., 1994. “Estimating Vital Rates from Corporate Data Bases: How Long Will GM’s Salaried Retirees Live?. In H. Kintner, T. Merrick, P. Morrison, and P. Voss (Eds.) Demographics: A Casebook for Business and Government. pp. 265–295. Boulder, CO: Westview Press.
  3. Morrison, P. (2002). “The Evolving Role of Demography in the U.S. Business Arena.” Paper presented at the 11th Biennial Conference of the Australian Population Association, Plenary Session on Population and Business, Sydney, Australia, October 2–4.
  4. Robson, C. (1993). Real World Research. Oxford, UK: Blackwell.
  5. Siegel,  J.  (2002).  Applied  Demography:  Applications  to  Business,  Government,  Law,  and Public Policy. New York, NY: Academic Press.
  6. Siegel, S. J., & Swanson, A. D. (2004). The Methods and Materials of Demography. Elsevier Academic Press ISBN: 0-12-641955-8
  7. Stewart, D. W., & Kamins, A.M., (1993). Secondary Research, Information Sources and Methods. Newbury Park, CA: Sage.
  8. Swanson, D., Burch, T. & Tedrow, L., (1996). “What Is Applied Demography?” Population Research and Policy Review 15 (December): 403–418.
  9. United Nations Statistical Commission 2012.
  10. United Nations Workshop on Evaluation and Analysis of Census Data Nay Pyi Taw, Myanmar, 1–12 December 2014
  11. United Nations. (1985). Handbook of Vital Statistics Systems and Methods. Series F, No. 35. New York: United Nations.
  12. United Nations. (1998a). Handbook on Civil Registration and Vital Statistics Systems. Series F. No. 69, New York: United Nations.
  13. United Nations. (2008a). Handbook on Civil Registration and Vital Statistics Systems. Series F. No. 69, New York: United Nations.

    Suggested Readings

  1. Survey of Research in Demography by P.B. Desai.
  2. An Introduction to Population by O.W Kenneth and Kammeyer.
  3. Dynamics of Population and Family Welfare in India by Srinivasan and Mukerjee.
  4. Principals of Population Genetics by , A., Bhende and T. Kanitkar.