Tag: Demography

Population Estimation, Projection, and Forecasting

By Hansika Mehra

Abstract: Population estimation, projection, and forecasting are key tools in demography and urban/regional planning. Estimation refers to determining the current population size (typically between censuses) by adjusting the last census count with recent data on births, deaths, and migration. Projection involves creating future population scenarios under specified assumptions (e.g. fertility or migration trends). It is not a definitive prediction but a “what-if” extrapolation. Common projection methods include mathematical growth models (arithmetic or geometric extrapolation), the cohort-component method, and economic models. Forecasting goes a step further by integrating expert judgment and contextual factors to give the most likely future population. This essay reviews each concept in detail, outlines the main techniques (including India’s experience with cohort-component projections), and highlights their importance for policy and planning. Reliable population estimates and projections are essential for planning services (schools, hospitals, housing, etc.) and making informed policy decisions.

Introduction

Understanding population dynamics is critical for effective planning and development. Governments and planners must know how many people currently reside in an area and how that number may change over time. Between censuses, population projections and forecasts are the only practical means to track demographic change. In India and elsewhere, the last full population counts occur only once a decade. In the intervening years, demographers produce estimates of the current population and projections of future population sizes to guide resource allocation and infrastructure planning. For example, after the 2011 census, India’s Registrar General’s office projected future populations for states up to 2036. As Aryal (2020) notes, “accurate and consistent information [on population] are inevitable to planners, policymakers, administrators… for effective decision-making”. This essay explains what population estimation, projection, and forecasting mean, how they differ, and what methods are used for each.

Population Estimation

Population estimation refers to calculating the present size of a population when a recent census count is not available. It fills the “gap” between census enumerations. Estimation typically uses known demographic events or indicators since the last census to infer the current population. For example, one definition states that population estimation is based on “direct components of population change such as the actual number of births and deaths occurring between the date of the previous census and the date of the estimation”. In other words, we start with the last census count and add births, subtract deaths, and account for net migration to approximate today’s population. When complete vital statistics are lacking, indirect indicators may be used: for instance, changes in school enrollment numbers or vehicle registrations can signal how many people have been born or moved in an area.

Common techniques for estimation include mathematical interpolation or extrapolation and the use of administrative records. Mathematical methods might simply apply a constant growth rate (arithmetic or geometric) to estimate population between census years. Administrative records — such as civil registration of births and deaths, voter rolls, or ration card data — provide another source of information. Demographers may also conduct sample surveys (e.g. a Demographic and Health Survey) to estimate fertility and mortality levels and then apply those rates to update the population count. For example, one source notes estimating India’s population in 2024 by taking the 2011 Census figure and adjusting it with registered births, deaths, and migration data in the interim.

In practice, population estimates are often made yearly or quarterly by national statistical offices. These estimates inform current policy: for instance, districts use them to track progress on health indicators or to allocate budgets. However, estimation methods assume that trends continue uniformly in the short term and often overlook sudden events. Their accuracy depends on the quality of input data (e.g. completeness of birth/death registration) and may degrade rapidly if conditions change.

Population Projection

Population projections are calculations of future population size and structure under explicit assumptions. Unlike estimation, a projection concerns a future date: it answers, “what if” scenarios, not “what actually is”. One definition describes projection as “an estimation of the number of people expected to be alive at a future date that is made based on assumptions of population structure, fertility, mortality and migration”. In other words, we take current data and assume certain rates of births, deaths, and migration to compute the population at a future time. It is important to note that a projection is conditional: it shows what will happen if the assumptions hold, rather than a guaranteed outcome.

A key distinction often made is that projections are scenario-based and not firm predictions. Track2Training explains that projection is “not a prediction, but a ‘what if’ scenario based on specified conditions”. For instance, we might project a population under “high-fertility” and “low-fertility” variants to see a range of possible outcomes. Users should interpret projections with this in mind: they illustrate possible futures, not certainties. As the US Census Bureau notes, population projections are estimates for future dates usually based on assumptions about future fertility, mortality and migration. In contrast, estimates describe the population that has already occurred.

The most sophisticated and widely used projection method is the cohort-component method. This method advances each age-sex cohort of the population year by year, applying survival (mortality) rates and adding births for the youngest cohort based on fertility rates. In practice, the cohort-component method projects change in each five-year age group separately, accounting for mortality and age-specific fertility. Both the United Nations and India’s Registrar General rely on this method for long-term projections. As one analysis states, “Both UN and RGI [Registrar General of India] projections are based on the cohort component model, in which the components of population change (fertility, mortality, and net migration) are projected separately for each birth cohort or age-group”. This method provides detailed outcomes by age and sex, making it valuable for planning needs such as school enrollment or pension requirements. Its drawback is data intensity: it requires reliable estimates of current age structure, fertility rates by age, mortality rates, and migration flows. In countries with good vital statistics and census data, it yields the most credible projections.

In addition to cohort-component, demographers use several mathematical (often called “growth”) methods, especially when data are scarce or only short-term forecasts are needed. These include:

  • Arithmetic (Linear) projection: Assumes the population will grow by a constant absolute amount each period. For example, if a town added 10,000 people each decade in the past, one might project +10,000 each decade going forward.
  • Geometric projection: Assumes a constant percentage growth rate. For example, if the population has been increasing by ~5% per decade, the projection applies that fixed growth rate to each future period.
  • Exponential (Compound) projection: Similar to geometric but treats growth as compounding continuously. It uses the formula Pt=P0ertPt =P0 ert where r is the continuous growth rate.
  • Logistic and other curves: In some cases, analysts use logistic or Gompertz curves to model a decelerating growth as the population approaches a ceiling. These methods can capture the “S-shaped” growth seen when fertility is declining. However, logistic models require estimating a population “cap” or slowing parameter and are less commonly used for national forecasts.
  • Share-of-growth or Ratio methods: For sub-national areas (cities, provinces), forecasters sometimes assume that local population will change in proportion to a larger area’s growth. For example, if a state is projected to grow 20%, a city that was 10% of the state may be projected to grow similarly. One source lists “ratio method” among common techniques.

These mathematical methods are relatively simple and transparent, but they have limitations. They implicitly assume that past growth trends will continue unchanged (same birth/death rates) and usually cannot account for sudden shifts or age structure effects. For short periods (less than a decade), simple arithmetic or geometric interpolation between known census points may be acceptable, but for longer-range forecasts they often become unrealistic. As Aryal (2020) warns, mathematical methods assume an “unchanging socio-economic setting” and ignore irregular fluctuations. Such methods do not produce age-specific projections, only total population. Thus, they are often used when detailed demographic data are lacking or for quick checks, while longer projections rely on cohort-component.

A third category is the economic method of projection. This approach attempts to relate population change to economic factors. It operates on the principle that changes in birth, death, or migration rates are partly driven by economic development and social conditions. For example, economic growth may lead to lower fertility or change migration patterns. In practice, the economic method might involve regression or simulation models where demographic rates are functions of GDP growth, employment, or urbanization. Aryal (2020) explains that the economic method “tries to describe the way how economic factors influence the demographic factors i.e. birth, death and migration”. It recognizes that simple trend extrapolation ignores dynamic influences (e.g. a boom attracting migrants). In India’s context, however, this method is less often used at the national level. Aryal notes it is “less applicable” for country-wide projections, although it may be useful for regional or sectoral analyses (for example, forecasting urban migration in response to economic development). Overall, the economic approach is more complex and depends on accurate data about socioeconomic trends; it complements rather than replaces demographic methods.

Example (India): India’s official population projections (for 2011–2036) illustrate these methods in action. The Registrar General’s Technical Group used a mix of methods: for several small Northeastern states (together only ~1% of India’s population), they applied a simple mathematical (“arithmetic”) method due to sparse data. For the remaining states, they used the full cohort-component method, projecting each cohort by fertility, mortality and migration assumptions. These projections showed India’s population rising from about 121.1 crore in 2011 to roughly 152.2 crore by 2036. This example highlights how different methods may be applied to different contexts within one country.

Population Forecasting

Population forecasting refers to predicting the most likely future population, often for planning purposes. Unlike a bare-bones projection, which simply applies preset assumptions, forecasting incorporates expert judgment, policy knowledge, and consideration of uncertainty. Track2Training defines forecasting as “a prediction of the most likely future population based on past trends, present data, and expert judgment”. In other words, forecasters take projection results and adjust them using current information about policies, technological changes, or possible disruptions.

The key difference between projection and forecast is that a projection shows possible outcomes given assumptions, whereas a forecast attempts to state the expected outcome. For example, a projection might present scenarios where fertility is high or low; a forecast will select one scenario as the “best estimate” based on what experts believe will actually happen. In practice, forecasters often produce a single forecast (or a most-likely variant) and may provide high/low alternative scenarios around it. As the US Census Bureau notes, projections can come in multiple series (high, medium, low), but a forecast is usually interpreted as the “most likely” one among them.

Forecasting relies heavily on the forecaster’s judgment. A classic planning report observes: “Population forecasting is essentially a matter of judgment…This should be an informed judgment, backed up by the most complete and thorough analysis of the particular problem”. Forecasters must evaluate recent demographic trends and the factors behind them – such as changes in education, healthcare, or migration policy – and decide how these will play out. They may adjust projections to account for known upcoming changes (e.g. planned family programs, new immigration laws) or plausible shocks (e.g. a recession). For example, during the COVID-19 pandemic, forecasters needed to revise assumptions about mortality and migration in many countries.

In formal practice, a population forecast often starts with a baseline projection and then applies expert adjustments. The forecaster might consider demographic momentum, potential changes in fertility preferences, or government targets for birth rates. Sometimes forecasts are presented as a range: a central forecast plus optimistic/pessimistic variants. A US planning handbook explains that well-founded projections “are the best obtainable guides, but they are not infallible,” and cautions users that even a thorough forecast “may prove off the mark”. This humility is necessary because unforeseen events can alter trends.

Population forecasts are crucial for planning infrastructure and services. Planners use forecasts to answer questions like: How many schoolchildren will there be in ten years? Will we need to build new hospitals? How much housing will the city require? By integrating demographic projections with social and economic context, forecasts aim to inform such decisions. For example, a government might forecast the number of households to plan electricity grids or forecast the working-age population to model labor markets. In urban planning, accurate forecasts of city growth help in land-use and transportation planning. Although this essay is at the national scale, the same principles apply at regional or city levels, with perhaps greater uncertainty for smaller areas.

Conclusion

In summary, population estimation, projection, and forecasting are related but distinct tasks. Estimation determines the current or very recent population (usually using census data plus intervening birth/death records). Projection computes future population under specified assumptions, producing scenarios of what the population could be. Forecasting goes further by integrating expert judgment to predict the most probable future outcome, given policies and anticipated trends. Each of these tools serves planners: estimates update our picture of today’s population, projections outline possible futures under different demographic paths, and forecasts give a best-guess baseline for planning.

Across these tasks, the cohort-component method remains the gold standard for national projections, because it explicitly models births, deaths, and migration by age. Simpler mathematical methods (arithmetic/geometric) can be useful for short-term estimates or in data-poor settings. The economic method reminds us to consider broader drivers of change, though its practical use is limited by data availability. Forecasters must remember that all projection methods rely on assumptions about fertility, mortality, and migration. As noted in a US planning report, planners should always recognize that forecasts, however well-founded, “are not infallible”.

Nevertheless, having reliable estimates and projections is vital. Aryal emphasizes that population estimates and projections “provide accurate and consistent information” and are “essential tools for projecting to the future size and structure of population at national, provincial, [and] local” levels. In India, for instance, projected population figures guide everything from health service expansion to education enrollment targets. Globally, organizations like the UN use projections to track progress towards goals (e.g. sustainable development). In planning, these demographic tools help ensure that resources – schools, hospitals, housing, jobs – are matched to future needs. In conclusion, while no forecast can be perfectly certain, systematic estimation and projection techniques form the backbone of evidence-based planning. Keeping assumptions transparent and updating projections as new data arrive are key to improving their usefulness for society.

References

  • Aryal, G. R. (2020). Methods of Population Estimation and Projection. Journal of Population and Development, June 2020, pp. 54–60nepjol.infonepjol.info.
  • Track2Training (2025). Population Estimation, Projection, and Forecasting. (Blog article by Dr. Kavita Dehalwar)track2training.comtrack2training.com.
  • U.S. Census Bureau (2024). Population Projections. Census Academy Data Gem. Retrieved from Census.govcensus.govcensus.gov.
  • U.S. Federal Highway Administration (1967). Population Forecasting Methods: A Report on Forecasting and Estimating Methods. (Taylor and Hudson, Office of Planning, U.S. Department of Commerce)fhwa.dot.govfhwa.dot.gov.
  • People’s Archive of Rural India (2020). Population Projections for India and States, 2011–2036. PARI Library (Summary of RGI technical report)ruralindiaonline.orgruralindiaonline.org.
  • Bhattacharya, Pramit & Mishra, Nandlal (2024). Population projections and their track record. DataForIndia, Nov 26, 2024dataforindia.comdataforindia.com.
  • Census of India (2019). Population Projections for India and States 2011–2036. Technical Group report (see PARI summary)ruralindiaonline.orgruralindiaonline.org.
  • Aryal, G. R. (2020). Methods of Population Estimation and Projection (continued). Journal of Population and Development, June 2020nepjol.infonepjol.info.
  • Aryal, G. R. (2020). Methods of Population Estimation and Projection (conclusion). Journal of Population and Development, June 2020nepjol.info.
  • Census Academy (2024). Population Projections – How are they done?. U.S. Census Bureau info sheetcensus.govcensus.gov.

Study of Demography: Source of Demographic Data

BySanchana Siva Kumar

1.Abstract:

Demographic data comes from traditional sources like censuses, surveys, and administration records, which provide comprehensive information for policy and research. More recently, new data sources like “big data” from sources such as mobile devices, social media, and satellite imagery are being used to supplement and analyse population trends in new ways. Each source has advantages and disadvantages, and countries often use a combination of these methods. 

Demographers use demographic data taken from various sources to analyse population. A demographer is an expert in the study of statistics relating to the changing structure of human populations. It is well known that the three main sources of demographic and social statistics are censuses, surveys and administrative records. These three data sources are the principal means of collecting basic demographic and social statistics as part of an integrated program of statistical data collection and compilation.  Together they provide a comprehensive source of statistical information for policy formulation, development planning, administrative purposes, research and for commercial and other uses. While these three sources are complementary, many countries use a combination or all three methods for various reasons.  Normally, countries select one of these sources to obtain statistics based on the needs of the respective data users; reliability and timeliness of the results; and practicality and cost-effectiveness of the method. In many countries, however, a particular method is used due to statutory requirements.

Some main sources of demographic data collected by demographers are

1.1 Population and housing censuses:

Population censuses have been carried out in almost every country of the world during the past several decades, and some countries have conducted censuses for more than a century. The main reason censuses are carried out by so many countries is because a population census is the only data source which collects information from each individual and each set of living quarters, normally for the entire country or a well-defined territory of the country. Censuses must be carried out as nearly as possible at a well-defined point in time and at regular intervals so that comparable information is made available in a fixed sequence (United Nations, 1998).

1.2 Sample enumeration in censuses:

The cost and limited number of questions that can be included in the questionnaire are the main disadvantages of a population and housing census, so many countries carry out a sample enumeration in conjunction with the census to collect more detailed information on a separate (longer) questionnaire, often referred to as the “long form”. Collecting additional topics from a sample of population or households during the census operation is a cost-effective way to broaden the scope of the census to meet the increasing and expanded needs for demographic and social statistics. The use of sampling makes it feasible to produce urgently needed data with acceptable precision when factors of time and cost would make it impractical to obtain such data from a complete enumeration.

 1.3 Household sample surveys:

Household surveys are the most flexible of the three data sources. In principle, almost any subject can be investigated through household surveys.  With much smaller workloads than in censuses and the opportunity to train fewer personnel more intensively, household surveys can examine most subjects in much greater detail. While it is not possible to anticipate all the data needs of a country far into the future at the time a census is being planned, household surveys provide a mechanism for meeting emerging data needs on a continuing basis. As budgets for national statistical activities are always limited, the flexibility of the household survey makes it an excellent choice for meeting data

users’ needs for statistics which otherwise are unavailable, insufficient or unreliable.

1.4 Administrative records:

The third important data source that is commonly used in many countries is administrative records. The statistics compiled from various administrative processes can be very valuable to the overall national statistical system. Many social statistics are produced as a by-product of these administrative processes—for example, education statistics from periodic reports by the ministry of education, health Statistics from periodic reports based on hospital records, employment statistics compiled from employment extension services and so forth. Demographers use those sources to collect demographic data.

2.INTRODUCATION:

The term “Demography” is the statistical and mathematical study of the size, composition, and of spatial distribution of human population, and of the changes over time in these aspects through the operation of five processes of fertility, mortality, marriage, migration and social mobility. Usually, the demographic data are drawn from various sources such as national censuses, civil registration system as well as the sample surveys.

The three main conventional sources of demographic data are censuses, vital statistics, and sample surveys. A census captures a comprehensive snapshot of a population at a specific moment, offering detailed demographic, social, and economic data for the entire country. Vital statistics, collected through a civil registration system, provide a continuous record of crucial life events like births, deaths, marriages, and divorces. Sample surveys collect data from a representative portion of the population, offering a more flexible and cost-effective way to supplement census and registration data with specialized information. The integration of these complementary data sources allows demographers to build a robust and comprehensive picture of a population’s past, present, and future.

This data is crucial for demographic analysis, which in turn informs public policy, economic and market research, and social development initiatives.

 3.DISUSSION:

THE IMPORTANT SOURCES OF VITAL STATISTICS IN INDIA ARE:

  1. POPULATION CENSUS
  2. CIVIL REGISTRATION SYSTEM
  3. DEMOGRAPHIC SAMPLE SURVEYS SUCH AS THOSE CONDUCTED BY THE NATIONAL SAMPLE SURVEYS ORGANIZATION (NSSO)
  4. SAMPLE REGISTRATION SYSTEM (SRS)
  5. HEALTH SURVEYS, SUCH AS NATIONAL FAMILY HEALTH SURVEYS (NFHS)
  6. DISTRICT LEVEL HOUSEHOLD SURVEYS (DLHS-RCH) CONDUCTED FOR ASSESSING PROGRESS UNDER THE REPRODUCATION AND CHILD HEALTH PROGRAMME

3.1POPULATION CENSUS:

It is compiling, evaluating, analysing and publishing demographic, economic and social data pertaining, at a specific time, to all persons in a country or in a well-delimited part of a country.” In other words, the enumeration of a country or a region at a particular time is known as census.

The most important source of demographic data is the census. The word “census” is derived from the Latin word censure which means “to assess”. The New International Webster’s Dictionary defines it thus – “An official count of the people of a country or district including age, sex, employment, etc.” A United Nations Study defines the population census as the “total process of collecting, compiling and publishing demographic, economic and social data pertaining, at a specified time or times to all persons in a country or delimited territory.” Thus, a population census is an official enumeration of the inhabitants of a country with statistics relating to their location, age, sex, marital status, literacy status, language, educational level, economic activity, number of children, migration, etc.

Population census is a regular feature of all progressive countries, whatever be their size and political set up. It is conducted at regular intervals, usually every 10 years, for fulfilling well-defined objectives.

Salient Features of Census:

 A census has the following features:

 1. A census is usually conducted after an interval of 10 years.

2. The census covers the entire country or a part of it.

 3. The census operations are completed within specified dates.

4. It is organised and conducted by the Government through the Census Commission of the country.

5. For conducting the census, a reference period is determined by the Census Commission at that point of time.

6. A household or family is treated as a unit. However, in large census operations, migrant individuals and homeless persons are also enumerated at night at their places of rest or sleep.

7. Before starting the census operations, some preliminary steps are taken by the Census Commission such as preparation of schedules, lists of households in each area, training of enumerators, etc.

8. The filled-up census schedules are collected, examined and analysed statistically by the Census Commission.

9. The census data are published for circulation.

10. The census operations involve collection of information from households from door to door by enumerators. In some countries, schedules are sent by post and the required information is collected.

11. A census is a process whereby information is collected relating to age, sex, marital status, occupation, education etc. from people residing in a country.

12. Every country is legally bound to undertake a census after an interval of 10 years and people are bound to cooperate and provide the required information.

Uses of Census:

 Population census is very useful for researchers, administrators, social organisations, etc.

We highlight its uses as under:
  1. It provides primary population data relating to age, sex, marital status, economic activities, occupations, migration, literacy, etc.
  2.  Population data throw light on the socio-economic problems of the country such as the status of women, male-female sex ratio, population density, literacy level, urbanisation, living standards, etc.
  3.  These data help researchers, administrators, planners and social organisations to suggest and adopt measures to solve the various problems.
  4.  Census data are used for constructing life tables by insurance companies.
  5.  They are highly useful for making population projections.
  6.  Census data are used for carrying out sample surveys.
  7.  They are used by the Election Commission of the country for demarcation of constituencies and allocation of seats for municipal corporations, state legislatures and parliament of the country.
  8.  Population data are one of the bases of allocation of resources between the centre and states in a federal country.
  9. They guide the city planners in planning measures for the future growth of cities regarding their future needs relating to housing, transport, flyovers, sanitation, pollution, water, educational institutions, etc.
  10. Population projections and age-sex structure of the population help the government in estimating for the future military personnel of the country.

Some Problems of Census:

 Census operations are costly in terms of men, materials and money. They require huge manpower, piles of forms containing schedules and lot of money on them and on processing, preparing and publishing population data. The entire census work is also very time consuming.

 Besides, there are some other problems listed below:
  1. Census is not a continuous process and is usually conducted after 10 years. So, this is an ad hoc work which requires the training of census staff before each census. Thus, experienced staff is not available.
  2.  The enumerators often interpret the terms used in the schedules in their own way despite the guidelines supplied to them by the Census Commission.
  3.  In the census operations, the enumerators are required to go from door to door to collect information. This work is not only time consuming but also monotonous. Some enumerators who shirk work and are dishonest fill up the schedules with cooked up figures sitting at home.
  4.  Often many persons are reluctant to provide correct information for fear that it may be used for some other purposes. This happens if the household is illiterate or the enumerator is not able to convince the former that the entire information is kept secret by law.
  5. The household schedule pertaining to the census does not have any column about the number of family members who might have gone abroad.
  6.  In many developing countries, the column in the household schedule relating to age is based on age groups 1-5, 6-10, etc. thereby leaving a wide gap of 5 years. This creates a problem for the enumerator to fill up the age column which becomes a mere guess work. This is a defective method because age- specific information cannot be collected. In India and developed countries, age at the last birth in completed years is taken.
We may conclude with Barclay:

 “In practice, some people are always missing. It is impracticable to include all cases which belong to the universe. Some cases which ought to be covered according to rule are always omitted. On the other hand, some may be recorded more than once.”

HOW THE NATIONAL CENSUS IS TAKEN:

Census taking is a very complex and extensive task and is, therefore, usually conducted by governments. In many countries, provision for census taking is made by law. While such a law males the co-operation of each citizen mandatory, it also ensure that confidential nature of census information provided by individuals shall be preserved.

In India, census taking has been the responsibility of the government from the vary beginning. Even today, population census is a union subject, with the Ministry of Home Affairs in charge. A senior officer of the Indian Administrative Service, with experience in the conduct of census operations, is generally appointed as census commissioner. There are thousands of enumerators, with a hierarchy of officers at various levels in between. For each state and union territory, an officer, designated as the director of census operations, is appointed.

Taking into consideration the magnitude of the tasks, entire administrative machinery of the state and local self-government is placed at the disposal of the director of the census Operations. In rural areas, primary school teachers, village “patvaris” and other staff in local officers are generally appointed as census enumerators. The enumerator is the basic and the most important link in census operations. He has to visit every household within the area assigned to him and collect the required information.

3.2 Registration:

 Another source of population data is the registration of life or vital statistics. Every person is required by law to register with a specified authority such demographic events as birth, death, marriage, divorce, etc. Unlike the census, registration of vital events is a continuous process throughout the year.

It is an important source of information about citizenship, marital status, succession rights and settlement of disputes regarding birth and death.

 Registration is a secondary source of demographic data which is available from four sources:

(1) Vital Registration;

 (2) Population Register;

 (3) Other Records, and

 (4) International Publications.

They are explained as under:

3.2.1Vital Registration:

 Recording of vital events (or vital statistics) like births, deaths, marriages, divorces, etc. is obligatory on the part of every citizen in a country. For instance, the birth of a child has got to be registered with the municipal corporation of the town where the child is born in India.

Similarly, the occurrence of a death is required to be registered.

Such registration involves the filling up of a proforma with the following columns in each case:

 Birth Certificate: Name, Father’s Name, Mother’s Name, Age of Father, Age of Mother and Legitimacy.

Death Certificate: Name of the deceased, date of death, sex, race/caste, age of the deceased, place of death, cause of death, occupation, marital status, permanent residence, etc.

 In developed countries and in many developing countries, registration of marriage is also compulsory. But it is not so in India. Very few people want to register marriages with the Registrar of Marriages in developing countries like India. Bangladesh, Pakistan and Sri Lanka.

Similarly, in almost all the developing countries where the majority of people are illiterate and reside in rural areas, births and deaths are not reported to the registration authorities. Thus the registration records remain incomplete and are imperfect source of demographic data.

But this is not the case in developed countries where people are educated and record births, deaths, marriages, divorces, etc. with the appropriate authorities.

3.2.2 Population Register:

 This is another secondary source of collecting population data. A number of  maintain permanent population register for administrative and legal purposes.

It contains the names, addresses, age, sex, etc. of every citizen, of those who migrate to other countries and who enter the country. The population registers helps in verifying the correctness of the census figures for that year.

3.2.3 Other Records:

Besides the population register, there are other records which are secondary sources of demographic data in developed countries. They maintain population records to meet social security schemes like unemployment insurance and allowance, old age pension, maternity allowance, etc.

 In some countries, insurance companies maintain life tables relating to births and deaths and population trends. Selective demographic data are also available from electoral lists, income tax payers’ lists, telephone subscribers’ lists, etc. Though such administrative data are limited, they are helpful in providing for carrying out sample surveys.

3.2.4 International Publications:

Other sources of demographic data for the world and different countries are the United Nations Demographic Year Book and Statistical Year Book. The World Health Organisation (WHO) publishes a monthly journal Epidemiological and Vital Records which gives data on public health and mortality of different countries.

The United Nations Development Programme (UNDP) in its Human Development Report and the World Bank in its World Development Report publish annually demographic data relating to population growth, projections, fertility, mortality, health, etc. for countries of the world.

3.3 Sample Surveys:

 Sample survey is another source of collecting population data. In a sample survey, information is collected from a sample of individuals rather than from the entire population. A sample consists of only a fraction of the total population. Several different population samples can be drawn on the basis of sample surveys such as the number of abortions, contraceptives used, etc. for the study of fertility.

Some countries conduct national sample surveys based on Random Sampling or Stratified Random Sampling. Whatever method is adopted, care should be taken to select a representative sample of the total population. The survey of the sample requires a small trained staff and small questionnaires relating to one aspect of the population. The data so collected are tabulated, analysed and published.

 So this method takes less time and is less costly. Sample survey can be used to supplement the census data and to carry out further the trends in population growth in between two census operations. Sampling is also used to check the accuracy of the census data where there is doubt in census results. This method yields good results if the sample is properly chosen.

Limitations:

The sampling method has certain limitations.

  1. It is highly subjective and it is possible to arrive at different data with different samples of the same population.
  2. There are bound to be errors in coverage, classification and sampling of population data.
  3.  As the survey requires many surveyors who may not be efficient and sincere, it is subject to large errors.
  4.  If the informants in the sample do not cooperate with the surveyors, the survey will not give accurate results. To conclude with Stephen, “Samples are like medicines. They can be harmful when they are taken carelessly or without adequate knowledge of their effects.

 

4.Conclusion:

 The study of demography relies on a combination of data sources like censuses, civil registration, and surveys, each with unique strengths and weaknesses, to understand population dynamics. Accurate demographic data is vital for informing policy, planning public services, and driving economic and social development, and the integration of modern data sources like big data is transforming the field. Ultimately, a multi-source approach is necessary to get a comprehensive and reliable picture of a population. 

Demographic data is data one of the essential characteristics of the population. This includes age, gender, and income as well. It is used in nearly all the fields of a country for estimating their customers and their characteristics. The prevalent research methods like civil registration systems, census, and sample surveys are some of the most common and popular research techniques. Each of these has many advantages and disadvantages, like in the civil registration system; the data may not be updated timely, leading to wrong evaluation.

In the census method of research, the surveyors are supposed to reach door to door, which is highly time-consuming and monotonous, leading them to act disloyal and not provide truthful information to their superiors. In the sample survey method, the chosen samples may be inappropriate and not lead the surveyors to the best results. Seeing the importance and need of accurate demographic data, a lot of newer research methods are being launched, which can reduce the hard work of the organisations and ease the process with less or no involvement of humans and other expensive sources.

The study of demography depends on a combination of primary sources (census, vital registration, surveys, population registers) and secondary sources (administrative records, special studies). Each has its strengths and weaknesses, but together they provide a comprehensive picture of population dynamics. Accurate demographic data is essential for planning development policies, health care, education, housing, and employment.

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Analysis and Study of Crude and Age Specific Mortality Rates

By Swastika Sarkar

Abstract:

Crude and age specific mortality rates are important factors for the study of epidiemology and also to understand the demographic characteristics of a particular area, city, district, state or country. It is a very important as well as useful in accounting various demographic characteristics and also to identify where it is lacking and the reason behind its lacking. Through this life expectancy, longevity, migration, standardization can be done which is useful in calculating various other forms of demography and will help in understanding a lot of factors. Crude mortality rate means  the TOTAL NUMBER OF DEATHS IN PARTICULAR POPULATION (MOSTLY ACCOUNTABLE IN A POPULATION OF 1000 PEOPLE) while age specific mortality rate is defined as the TOTAL NUMBER OF DEATHS IN A PARTICULAR AGE GROUP TO THE TOTAL NUMBER OF PERSONS IN THAT AGE GROUP IN A POPULATION OF 1000 PEOPLE. Life table helps in the calculation of CRUDE DEATH RATES and is helpful in estimating the overall death rates and also the causes behind it. AGE SPECIFIC DEATH RATE is calculated between the beginning of age ‘x’ upto the beginning of age ‘x+1’.

Keywords: Crude death death, Age specific death rate, demography, population.

Introduction:

The public health department demands of including mortality rates which gives an overview of the well being of the population. These mortality rates identifies the state of well being of various sociodemographic groups around a particular region, state, city, district or even country. Like in case of India the census is responsible for conducting various surveys on various socio-demographic characteristics like birth rate and their types, age sex composition etc. in this the crude mortality rate and the age specific mortality is also accountable and is essential for explanation of various problems and also the criteria for ending up those problems. Actually mortality is dependent on various factors like age, gender, ethnicity and place of residence. Usually it is seen that the females live more than the males due to various hormonal activities and also the physical condition. Like the old aged people and children and infants are prone to more to mortality than the middle aged people. Like in 1971 the crude death rate is only 7 per 1000 population and urban estimates are lower than the rural estimates as it has more advanced infrastructure and hospitals and healthcare facilities. 

Discussions:

There are various aspects to discuss about the Crude Mortality Rate and the Age Specific Mortality Rate like what are the meaning of those, what is the importance of these two, why one should study them, what is the reason behind studying them, etc. These questions can be answered as well as understood easily if case studies between the Developed, Developing and Under-developed countries will be provided. From each types two countries will be chosen and further discussions will be made according to that. In Developed Countries, USA and Italy will be taken into discussions and likewise in Developing countries, India and Brazil and in Under-developed countries, Afghanistan and Ethiopia will be taken into action to understand the two concepts, Crude Mortality and Age Specific Death Rate.

DEVELOPED COUNTRIES

USA:

Crude Mortality Rate is very much high in the USA. It is 923 deaths per 1,00,000 population. Major reasons behind the deaths are heart diseases(highest), cancer, accidents(unintentional injuries), stroke(cerebrovascular diseases), chronic lower respiratory diseases, Alzheimer’s disease, diabetes, Nephrone related diseases and chronic liver diseases and cirrhosis. Moreover, during the pandemic Covid-19 the number of deaths are very high(49,932 deaths). Why this happens and how is the infrastructure related to all these will be discussed. 

Life expectancy in US in the year 2023 was 78.4 years an increase of 0.9 years from the previous year of 2022. Age adjusted death rate was reduced from 6.0% from 798.8 deaths per 1,00,000 population in 2022 to 750.5 in 2023. The Age Specific Death Rate decreases for all the age groups between 5yrs and also the elderly people. The death rate decreased from 3.9% for age group 5-14yrs, 3.4% for 15-24yrs, 9.4% for 25-34yrs, 7.1% for 35-44yrs, 9.2% for 45-54yrs, 9.3% for 55-64yrs, 8.5% for 65-74yrs, 7.7% for 75-84yrs and 0.7% for 85 and older. There was a distortion in this death rates during the outbreak of Covid-19 like the elderly and the children death rates are higher as their immunity is much more less than the mid aged persons and the youth. It is seen that the death of males from heart disease is more than the females. In Covid-19 also the ratio is same, while in the case of Alzheimer’s and dementia related diseases the female death rate is more than males. It happens because females have various responsibilities to manage like managing the household, taking care of the kids, dropping them to school, managing own work and office, taking care of the husband and the family. 

ITALY:

Crude Death Rate in Italy is relatively lower than other countries. It is 11.20% in the year of 2023. This happens as it has better infrastructure, healthcare facilities, and also less societal norms. This country has also less amount of pollution as it used more number of NMT or Non Motorised Vehicles like cycles, EV vehicles or buses and also walking. They also used public mode of transport and as a result pollution is less and mortality rate is also less. But regarding all this the death rate which is there is due to the old aged problems, any accidents etc. The death rate is highest in this country during the outbreak of Covid-19, the death rate is one of the highest during that time as the number of old aged people are more and the pandemic is more effecting the old aged people than the other age groups.

The population growth rate is -0.2% which means population is declining and there can be various reasons behind it like high mortality rate or low birth rate with standard mortality rate or high birth rate and high mortality rate. The reasons behind it has to be identified. From the graph it is analysed that the male population is significantly decreasing in the year 2050, this can be done by population forecasting method. Again the life expectancy for female is 84.3yrs whereas the life expectancy for the male is 80yrs only which is again same as the life expectancy of USA. The deaths due to stroke is more in females than in males. The death from lung cancer is relatively higher in males from which an assumption can be made that males smoke more than the females. In 2021 the main cause of deaths of all age groups is Covid-19.

DEVELOPING COUNTRIES

INDIA:

In India the crude mortality rate is significantly decreasing in the past few decades which shows us that the infrastructure has been improved and also the societal characteristics and tantrums have been removed. This decreasing mortality rate increases during the time of Covid-19 and after recovering the outbreak it again decreases.

We all know that India is a diverse country with various states, languages, cultures, social belief. So the age specific mortality is different for different for different states. Like in the states of Bihar and Jharkhand the mortality rates for female and children is higher which shows that the infrastructure and the healthcare facilities are not upto the mark and as a result death happens. This also can be happened that various females can die during the time of giving birth as the facilities which are required for saving both the child and the mother is not there. Then comes the old age population whose death rate is higher after the female and child death rate.

BRAZIL:

In Brazil also the crude mortality rate is also decreasing in the past few decades which shows again that the infrastructure and other healthcare as well as other facilities also improved and also the societal pressure and tantrums are also decreased. There is a distortion of this trend during the outbreak of Covid-19 as the mortality rate increases during that time and after that the trend becomes equal that is it is decreasing.

The population growth rate is 0.4% which is acceptable and that means that the birth and the mortality rates are balanced and the role of infrastructure in balancing the population growth is immense. The maximum population lies between the age groups of 15-64yrs and the least population is between 0-14yrs. By 2050 it is seen from the graphical projection and the population forecasting that the youth population including both males and females decreases whereas the population of the old aged people like above 85+ increases, this indicates that the birth rate will go beyond the death rate and as a result the population will get decreased.

UNDER-DEVELOPED COUNTRIES

AFGHANISTAN:

In Afghanistan also the death rate decreases that is very common in all of the above countries which are discussed but one peculiar thing about this country is that the death rate remains decreasing even at the time of outbreak of Covid-19, this indicates that the number of affected person is much more less than the other countries like Italy, USA, India and Brazil and other countries also because the death rate all over the World increases but here it decreases it indicates that the infrastructure and also the center of power is much more powerful to fight against the outbreak of this pandemic.

The population growth rate is 2.2%, it is quite high with respect to the other countries because of the social tantrums as well as the infrastructure and also center of power. The growth rate is high because the infrastructure is poor and also they do not have the proper facilities which should be provided to a particular citizen. And the government there also do not take any measures regarding the control of birth rate like in various European Countries they have rules that a particular family will not have more than 2 children but such kind of rule is not there and we all know that Afghanistan is mainly a Muslim dominated country so there are also social cultures regarding controlling of the fertility rate.

ETHIOPIA:

   In Ethiopia, like in Afghanistan also the death rate is also decreasing. The death rate is very high during the 1960s but it gradually starts decreases and also the same peculiar thing is happened here that the outbreak or the death rate due to Covid-19 is also less compared to the other European and American countries, this implies that the immunity system of this country is more higher than the other countries and as it is an under developed country so the infrastructure facilities is also not very advanced or so much up to date. So the immunity alone is responsible for saving the country from the spread of Covid-19.

The population growth is 2.6% and it is the highest among the above four discussed countries and this happens because the literacy rate is very much less and as a result they don’t have enough learning that the more number of children will create only trouble. They only understand that if there are more number of children then the number of earning members will be more and as a result they can live their life easily. The death rate is highest by lower respiratory diseases in males and this happens because of malnutrition and lack of healthcare facilities.

Conclusion:

Crude Death Rate (CDR) and Age-Specific Death Rate (ASDR) are both vital indicators used in demographic and public health studies to assess mortality patterns within a population. The CDR measures the total number of deaths per 1,000 individuals in a given year, providing a broad overview of mortality. However, it does not account for the age structure of the population, which can lead to misleading comparisons, especially between countries or regions with significantly different age distributions.Age-Specific Death Rate (ASDR), on the other hand, measures mortality rates within specific age groups. This allows for a more detailed and accurate understanding of mortality risks and patterns. ASDR is particularly useful in identifying vulnerable age groups, evaluating the impact of health interventions, and developing targeted public health policies.While the CDR is useful for general assessments and trend analysis over time, ASDR is essential for more nuanced evaluations and effective decision-making. Together, both indicators complement each other and provide a comprehensive picture of mortality in a population. Understanding and analyzing both rates is crucial for health planning, resource allocation, and improving population health outcomes across different age groups.

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