31 Population and development: basic concepts

Suman Dua

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1. Demography

 

Demography can be defined as the “scientific study of human populations, primarily with respect to their size, their structure and their development” (Van De Walle, Multilingual Demographic Dictionary, 1982). There is however some tension as to what exactly “demography” exactly encompasses. For some, it comprises “a set of techniques by which data collected in censuses, surveys and vital registration systems about age, sex, births, deaths, migrations, marriages and so on are described, summarized and manipulated” (Newell, p.3). This is often referred to as “formal demography”. For others, it is much broader and encompasses the study of fertility, mortality and migration from a variety of different viewpoints including sociology, economics, anthropology etc… As such it is inherently multidisciplinary and it is often referred to as “population studies”, a term which also includes the treatment of relation between demographic phenomena and social, economic or political phenomena.

 

1.1 Rate in Demography

 

The term “rate” in demography, relates a number of events (such as births, deaths, migrations) in its numerator, to a number of “person-years of exposure to risk” experienced by a population during a certain time period in its denominator.We can say that a rate measures the speed at which events occur,in a oversimplified expression.

 

The definition of a rate has several important points :

  • rate refers to a given period of time that has to be specified, not just to a number of people. Rates are frequently calculated for a period of one year (annual rates), but they may also refer to shorter periods (e.g., daily or monthly rates) or longer periods (e.g., 10 years, a century).
  • rates in demography are calculated per “person-years”, rather than simply per year or per person. Why is that necessary? In many situations the amount of time at risk of experiencing an event (e.g., giving birth) differs between members of a population. Think of the US population: each year a certain number of people die, or move out of the country. Women of reproductive age who die of an accident in July are not exposed to the risk of giving birth for the same duration as other women who have remained alive during a given year. The former are exposed to the risk of giving birth for 6 months, whereas the latter are exposed to the risk of giving birth for 1 year. We say they do not contribute as many person-years of exposure to the denominator.
  • Third, “person-years” needs to be qualified. We add “of exposure to risk”, and by this we aim to limit who is included in the calculation of a rate to those who may experience an event. For example, women in their 70’s and 80’s never bear children, so they are not at risk of giving birth. As a result, they are excluded from the calculation of fertility rates: fertility rates are frequently limited to women aged 10-49, or 15-49.

    Many measures often referred to as “rates” in demography and elsewhere however are not strictly speaking “rates”. For example, the crude birth rate ( = # of births / total population ) is really a ratio since it includes in its denominator males, children and the very old: these groups are not at risk of giving birth.

 

Some of the key measures in demography are listed below:

 

1.2.Sex ratio

 

The sex ratio is the ratio of males to females in the population (normalized to 100). We calculate two sex-ratios: at birth, and in the total population.

 

The sex ratio at birth is fairly standard, around 105 men for 100 women. Due to higher mortality among males, the sex ratio in the total population switches to 95-97. For populations with high levels of sex-selective outmigration (such as male soldiers leaving a country for war), particularly in certain age groups (e.g. aged 15-29), the sex ratio may be even smaller.

 

1.3.Dependency ratios

 

This ratio quantifies the number of persons in a population who are not economically active for every 100 economically active persons in that population. It can be calculated by dividing the population 0-14 years and 65 years and older by the population that is in the 15-64 year age group.

 

You can calculate separate dependency ratios: child dependency ratio (Pop 0-14 / Pop 15-64) and old age dependency ratio (Pop 65+/Pop 15-64).

 

Ranges for child dependency ratios

  • Least Developed: 80.8
  • Developing: 53.1
  • More Developed: 29.4

    1.4.Maternal mortality ratio

 

The maternal mortality ratio (MMR) is the number of maternal deaths per 100,000 live births. The numerator only includes deaths to women during their pregnancy or in the first 6 weeks after delivery.

 

Ranges for the MMR

  • Least Developed: 1000
  • Developing: 440
  • More Developed: 12

    1.5.Crude Birth Rate (CBR)

 

Number of births per 1,000 persons in a population over a given period of time (i.e. 1 year).

 

Ranges of CBR

  • Least Developed: 40.4
  • Developing: 23.1
  • More Developed: 11.2

    1.6.Crude Death Rate (CDR)

 

Number of deaths per 1,000 persons in a population over a given period of time (i.e. 1 year). CDR is calculated in the same way as for CBR, but with deaths instead of births as the numerator.

 

Ranges of CDR

  • Least Developed: 14.9
  • Developing: 7.8
  • More Developed: 10.2

    1.7.Age Specific Death Rates (ASDRs)

 

In describing a population phenomenon like mortality, rates are often calculated for specific age groups of the population to gain a more sophisticated picture of how the population is changing over time. This is especially important for gauging the efficacy of health interventions that are targeted at specific segments of the population such as children or the elderly. Very high death rates among children under 1 year of age may require a very different intervention than would very high death rates among adults over 70 years of age. They are usually expressed per 1000 persons.

 

1.8.Infant Mortality Rate (IMR)

 

Infant mortality is the annual number of infant deaths among infants (i.e., under the age of 1 year) divided by the mid-year population of all infants under the age of 1 year. However, because mid-year population is only available in certain countries and only for those years in which a census takes place, the most commonly used formula is as follows:

 

[Number deaths of infants <1 yr. in the current year] /[Number live births in the previous year] * 1,000

 

The IMR is the most widely used indicator of population health. Because an infant’s death is reflective of the mother’s well-being and nutritional status during pregnancy, the child’s nutritional status after birth and the child’s lack of protection against preventable, infectious diseases, a high IMR is an indirect measure of poor overall health and poor levels of living.

 

Range of IMR

  • Least Developed: 102
  • Developing: 56
  • More Developed: 8

  Other measures commonly used to describe health and mortality at young ages include: the neonatal mortality rate, the child mortality rate, and the under-5 mortality rate.

 

1.9.Age Specific Fertility Rate (ASFR)

 

Age-specific fertility rates are the total births in the calendar year to all women of the designated age group number of births to mothers of each age (or age group) by the number of women that age (or age group) in the population. This rate is usually expressed as births per 1,000 women of that age. ASFR can only be calculated with data on the age of the mother at birth of the child. For example the age-specific fertility rate of women aged 20-24 in 2005 can be written as:

 

Number of births to women aged 20-24 in 2005 / # of person-years lived by women aged 20-24 during 2005

 

2.One of the key goals of demography is to understand how populations change over time, i.e., their dynamics.

  • Do populations grow?
  • Do they become younger?
  • Do they age?

   To answer these questions, it is important to grasp what are the forces through which populations are transformed.

 

In the real world, populations grow or decline through a process of entries and exits. There are several ways through which individuals enter or exit populations. In the most general case (that of the population of a country), there are three categories of entries and exits: births, deaths and migrations. In fact, the size of a country’s population at any point in time (for example, 1/1/2010) can be expressed very simply as 1) the population a year earlier (i.e., 1/1/2009) plus 2) the number of births that have occurred in the population in the intervening year, minus 3) the number of deaths that have occurred in the population, plus 4) the number of immigrants who have moved into the population, minus 5) the number of emigrants who have moved out of the population. This is what demographers refer to as the “balancing equation”.

 

The difference between births and deaths is called a population’s “natural increase”, whereas the difference between the number of immigrants and the number of emigrants is the “net migration”.

 

The balancing equation applies to any population, at any point in time. It relates two stocks, i.e., two counts of individual members of a population taken at two points in time, by the flows that affect them. A flow is the number of events that have occurred within a population between two time points.

 

2.1.What Is a Population?

 

Until now, we have implicitly defined “population” very broadly, generally equating it to the population of a country. Populations however do not need to be as large, or to be confined within administrative boundaries: they simply represent a collection of individuals with a common characteristic. In the case of country, this common characteristic is residence. In public health, we also frequently define populations according to their risk behaviors (e.g., injecting drug users) or their medical history (e.g., cancer survivors). The techniques and tools of demography can also be usefully applied to such populations: for example, individuals may enter the population of injecting drug users in New York City by taking up injecting drug use or by moving from another city; they may exit the population if they quit injecting, are incarcerated or possibly die. The size (and growth) of the IDU population will depend on which flow is quantitatively more important.

 

2.2.Population Pyramids

 

Population pyramids represent graphically the age/gender structure of a population, i.e. how many men and women of a given age (or age group) are living in the population. They are a specific kind of histograms, in which (always): the male population is shown on the left side of the graph, and the female population on the right; the youngest are the “base” of the pyramid, whereas the oldest are at its top; the very oldest are generally omitted from the representation of the pyramid because it is impossible to depict this open-ended interval that contains a few of the oldest-old; percentages are calculated using both sexes combined (i.e., the total population) as the denominator.

 

A lot can be read from population pyramids: we can trace the history of a population, as well as project its future. In particular, one can infer the potential for population growth from a population pyramid. The two pyramids in the picture below represent typical populations.

 

The first pyramid, representing countries in West Africa, is typical of a population with high fertility and high mortality: high fertility means that there are a lot of children in the population and so the base of the pyramid is wide. By comparison, its top is very narrow because 1) mortality is high and people do not frequently reach the most advanced ages, but especially 2) due to high fertility, children systematically outnumber adults and the elderlies.

 

A few countries (mostly in Europe), on the other hand, have reached zero population growth or are experiencing negative growth because of low birth rates and an old age structure coupled with minimal net migration (countries in Europe try to close their borders to new immigration). In such countries, the base of the age pyramid becomes narrower than its upper parts, it is “shrinking”.By looking at population pyramids, one can also assess the potential for future growth of a population. The age pyramid of West African countries shown before has a lot of potential for future population growth: if the death rates decline, more and more of the numerous children in the population will survive to the age of childbearing. As a result, more and more women will bear children every year (even if on average each woman does not bear more children) and the births they have will further widen the base. As a result, the population will grow fast.

 

This is a very simple but critical point: today’s children are tomorrow’s mothers; today’s 55 year-olds are tomorrow’s retirees. Barring a few hypotheses about future trends in fertility, mortality and migration, demographers can thus use the information contained in population pyramids to project what a population may look like a few years down the road. For example, if we assume that women will keep baring children at the same rate and that people also keep dying at the same rate, then we can infer what the age-sex structure of the population will look like 10, 15 or even 50 years from now using simple arithmetic. An example of such projections is shown below.

  1. definition of development

    Important to first distinguish between:

 

3.1. Development as a state or condition-static

 

3.2 Development as a process or course of change- dynamicDevelopment is not purely an economic phenomenon but rather a multi-dimensional process involving reorganization and reorientation of entire economic

 

3.3 social system

 

Development is process of improving the quality of all human lives with three equally important aspects.

 

These are:

 

4. Todaro’s Three Objectives of Development

  1. Raising peoples’ living levels, i.e. incomes and consumption, levels of food, medical services, education through relevant growth processes
  2. Creating conditions conducive to the growth of peoples’ self-esteem through the establishment of social, political and economic systems and institutions which promote human dignity and respect
  3. Increasing peoples’ freedom to choose by enlarging the range of their choice variables, e.g. varieties of goods and services

    5. Alternative Interpretations of Development (Mabogunje) Development as Economic Growth- too often commodity output as opposed to people is emphasized-measures of growth in GNP. Note here the persistence of a dual economy where the export sector contains small number of workers but draws technology as opposed to traditional sector where most people work and is dominated by inefficient technology

 

6.Theories of Population and Development Interrelations

 

Population and development is a complex interrelated system, many variables are associated with both birth rates and rates of economic growth.

 

The evidence isless, inconsistent and inconclusive, suggesting that both arrows are working in the system

 

7. The Pessimistic Theories (orthodox view)

 

Supply of some natural resources (non-renewable) and capital is fixed. Supply would grow more slowly than the population

 

8. The main Points of Malthusian Theory are as follows

-Population tends to increase at a geometric rate

-Food can only increase arithmetically

-Population expands to eat up any surplus

-Subsistence wages forever unless moral checks

-Choose moral checks or positive checks

 9. According to NeoMalthusian Theory (Coale-Hoover,1958),the years,1940s-1960swasan era of unprecedented growth of population in the developing world.Coale and Hoover gave alternative projections of GNP for India and Mexico under assumptions of constant fertility and declining fertility as well as referred to Social expenditure on school and health due to young age structure diverted funds from capital investment.

 

Thus, according to Coale-Hoover Theory ,High population growth causes poor socio-economic development and the Policy Implications such that the Government should intervene to control population.The Limitations of Coale-Hoover Theory Are listed below:

 

Assumed economic growth as a function of onlycapital growth

Does not take into account the changes in technology and labor quality (through better heath and schooling of new generation)

Empirical evidence: Relationship not consistently negative (Blanchet)

 

10. According to Optimistic TheoriesPopulation growth exerts a positive influence on economic developmentandHuman ingenuity would create the technology to overcome any environmentalconstraints to development (Boserup, Julion Simon)

 

11.Marxism and Population refers thatA “Surplus population”is a creation of capitalism, and a necessary condition for its continuance.Capitalism requires a surplus of readily exploitable manpower”which it creates by seizuring land, and by replacing workers with machines.

 

12.Revisionist Theory-1

 

According to the International Population Conference,1974: Development is the best contraceptiveTheory,as Underdevelopment produces rapid population growth.

 

Policy Implications should be to nvest resources in development activities–Set the world economic order right

 

12.1.Revisionist Theory-2

 

POPOULATION ≠DEVELOPMENT

International Population Conference, 1984, Mexico: USA position

Theory:   Population   is   a   ‘neutral’phenomenon   in   the   process   of   economic   developmentPolicy

Implications: Other issues must take priority, e.g. economic reforms, free markets, democracy etc.

 

13. Current Thinking(NAS,1986)

 

The scientific evidence : still inconclusive, links more clear at individual/household level rather than at national/regional level.Implication of rapid population growth vary considerably depending on economic, cultural, institutional and demographic differences among LDC. Population growth in not necessarily the principle cause of problems in LDC, but it does multiplies the damage caused by other world problems (unequal population distribution).Just slowing population growth can not solve such problems,but can contribute to their solution.

 

14. interrelationsICPD,1994, Cairo

 

Affirmation of Revisionist-2 with a new paradigm shift

 

Theory: Human rights are at the center of concerns for sustainable developmentPolicy implications should be towards Advancing gender equality, equity, and empowerment of women are key to population and development related program

 

The key concepts introduced in this session include:

Theories on inter-relationships between population growth and development

–Malthusian and Neo-Malthusian theories

–The consensus emerged from previous three International Conferences on Population

    15. Population growth and specific aspects of development

 

Population and deforestation, and agriculture development

Population and employment

Population growth and education

Population, food and nutrition

Population and water resources

Population and urbanization

 

15.1.Population growth, Agricultural Stagnation and Environmental

Degradation: The interrelationship

 

Multiple and synergistic links between rapid population growth,poor agricultural performance and environmental degradation

 

Relationships are difficult to analyze, as multiple factors affect rate of population growth,environmental degradation, and pace and direction of agricultural development

 

Boseruphypothesis: Agriculture intensification occurs as population density on agricultural land increases.Sub-Saharan Africa: Agriculture expansionrather than intensification. Expansive agriculture involved conversion of large areas of forest,wetlands, river valley bottoms, and grassland savanna to crop land. Agriculture expansion + rapid population growth = accelerated degradation of naturalresources = agricultural stagnation.

 

15.1.2. Factors Perpetuating the interrelationship

 

Deficiencies in economic policy environment (e.g. agricultural pricing, excessive control of agricultural marketing, lack of empowerment of farmers): Slowed the evolution of ancestral systems into systems more sustainable with higher population densityLack of rapid and widespread technological change

 

15.1.3. Traditional Tenure Systems And The Nexus

 

Rapidly rising population pressure makes effective common ownership regulation increasingly more difficultRapid population growth led to an erosion and breakdown in customary laws and rules governing sustainable use and management of land and other common property resources

 

15.1.4. Deforestation ,Fuelwood, and The Nexus

 

90% of households in Sub-Saharan Africa use wood-fuel as the staple source of energy.Slow economic growth will impede the switch to non-wood fuels.Hence the demand for wood-fuel would increase with population growth16.Labor Force and Population GrowthLabor force: population 15-65,who is actively seeking jobsGrowth of the labor force in future will depend upon:–Age structure of the population, younger the population-faster will be growth,Current fertility levels and economic activity rates by age and sex.

 

16.1.2. Jobs and Population Growth

 

Jobs boost labor demand, but definitely boosts labor supply-35 million people will enter global labor force/year,Interaction between population growth and unemployment more acute among nations with younger population-SSA has 45% population under 15 yearsMeasures to reduce population growth have a delayed effect on labor force size.

 

16.1.3.World Labor Force

 

Almost doubled since 1950s (1.2 billion to 2.7 billion) and currently One-third labor force is un/underemployed (ILO).Creation of 1.7 billion jobs is required to maintain current levels of employment in next 50 years.Almost all future growth will be in developing countries.

 

16.1.4.Aggravating Factors

 

Increasing acceptance of women’s labor force participation (may be offset by its effect on fertility?).Declining global per capita grain-land (traditional source of employment): declined by 50% in certain nations since 1950s and Slow pace of industrialization, are aggravating factors along with effect of HIV/AIDS epidemic.

 

7.Education and Population Growth: Global Situation

 

Between 2000-2050, the total population will increase by 47%, but population less than 15 years will decline by 3% (UN) due to overall slowing population growth rateNeed for education infrastructure will rise very slowly in next 25 years,and decline thereafter.Very young population coupled with persistent high levels of fertilityChild-age population will grow by 36% through 2030, before it begins to fallFor some countries, e.g. Uganda,Niger, Oman, the child age population will grow more than 50% by 2050.

 

8.Population and Forest Cover

 

Population growth and urbanization has Contributed to forest loss all over the world.Between the years,1960 and 1990 there has been loss of one-fifth of all natural tropical forest cover in Least Developed Countries.Asia lost onethird of its forest cover,whileAfrica and Latin America lost one-sixth of its tropical forest cover.

 

9. Policies Aggravating Environmental Consequences of Population areResource subsidies,Use of inefficient technologies for extraction of natural resources,Policies affecting population redistribution and Consumption patterns.

 

9.1 Population and Water Resources: A Precarious Balance

 

Water is notan infinite renewable resource.In both more developedand less developed countries, water supply exceeds sustainable supply .The increase in global demand for water for irrigation, household, and industrial use is predicted to be faster than the population growth.Increase in population affect both quality and quantity of water.Water is the function of both population growth and consumption patterns

 

9.2. Climate Change and Green House Emissions

 

There has been Global warming,rising of oceans,increased flooding,coastal erosion salinalizationof acquifers and coastal crop land.The Pattern of precipitation is also likely to change with global warming.Thereduced agricultural productivity is linked to both population increases , development and consumption patterns.

 

10. Demographic and societal consequences

 

There has been international and internal migration from rural to urban areas,as well as emergence of big cities and towns.There has been pressures on government social institutions e.g. schools and hospitals.Due to migration and industrialization there has been disruption of traditional family support systems and increase in crime rate.

 

Summary

 

The key concepts introduced in this module are Theories on inter-relationships between population growth and development, Malthusian and Neo-Malthusian theories and the consensus emerged from previous three International Conferences on Population. It also highlighted the relationship between population growth and agriculture,relationship between population growth, employment and education and the relationship between population growth and environment.Tried to relate population, development concepts.

you can view video on Population and development: basic concepts

 

References

 

US Resources

 

For US Data- different levels of analysis (country, state, city, health district, census tract, zip code), decide on appropriate level based on research question. Different sources of info are aggregated at different levels.

    International