21 Dynamics of age and sex structure

Anjali Kumari and Gautam Kshatriya

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Contents:

    1.  Learning objective of the dynamics of age and sex structure

2.  Introduction: Age structure

3.  Age sex pyramid

4.  Table 1. Percentage distribution of Population by age groups to total population by sex and residence, India, 2015

5.  Sex composition

6.  Measuring the Dynamics of the Age Transition

7.  Population Pyramids

8.  Average age and Dependency Ratio

9.  Growth Rates by Age

10.  The Age Transition

11.  Summary

 

Learning Objectives:

  1. To study the two attributes that largely influence an individual’s role in society.
  2. To study the importance of the data on population by age and sex for demographers, health administrators, for planning and evaluation of various developmental and health programs.
  3. To examine the classification of rural, urban, sex and marital status by age to unveil the characteristics of population composition.

    Introduction

 

The age and the sex structure of the population are the most important demographic characteristics that are captured by a census of a population. Age and sex are two attributes that largely influence an individual’s role in society. The data on population by age and sex is vital for demographers, health administrators etc. for planning and evaluation of various developmental and health programs. The classification of rural, urban, sex and marital status by age unveils the characteristics of population composition and provides disaggregated data for target oriented projects.

 

Age and sex influence the working of society in important ways because society assigns social roles and frequently organizes people into groups on the basis of their age and gender (the social component of sex). Age is a biological characteristic, but it is constantly changing; whereas sex is biological in nature, but does not change (except by human intervention in rare cases). It is the changing nature of age that creates such a dynamic process because younger people are treated differently from older people, and different kinds of behavior are expected of people as they move through different ages. At the same time, biological changes inherent in the ageing process influence what societies expect of people and influence how people behave. At very young and very old ages, people are more dependent on others for survival, and so the proportions of people at these ages will influence how society works. In the teen years, reproductive hormones influence behavior and every society has to deal with this phenomenon as well.

 

The idea that societies have separate sets of expected roles and obligations for people of different ages is captured by the concept of age stratification, whereas cohort flow captures the notion that at each age we are influenced by the historical circumstances that similarly affect other people who are the same age. The perspective of age stratification and cohort flow was first put forwarded as a cohesive package by Riley (1976a, 1976b) and Foner (1975). The notion of age status has been around for some time; Kingsley Davis noted in 1949 that “all societies recognize age as a basis of status, but some of them emphasize it more than others” (Davis 1949: 104).

 

The age stratification theory begins with the proposition that age is a basis of social differentiation in a manner analogous to stratification by social class (Foner, 1975).

 

AGE STRUCTURE

 

The age structure of a population refers to the number of people in different age groups in a country and it constitutes an important subject of demographic analysis and development planning. To an important degree, a person’s age influences what he needs, buys, does and his capacity to perform. Consequently, the number and percentage of a population found within the children, working age and aged groups are notable determinants of the population’s social and economic structure. The population of a nation is generally grouped into three broad categories: Children (generally below 15 years). They are economically unproductive and need to be provided with food, clothing, education and medical care.

 

Age structure is a important indicator of population composition, since a large size of population was in the age group of 15-59 indicates a large working population which require more expenditure on health care facilities. Similarly, high proportion of population would mean that the region has a high birth rate and the population is youthful.

 

India has high birth rate which in turn shows an age structure which is typical of the countries of less developed region- a very broad base and a tapering top. In demographic terms such an age structure is known as “young population”. Nearly 40% of India’s population, according in the 2011 census, is below 15 years of age and only 6.9% is aged 65 years and above.

 

A larger percentage of the dependent population tends to reduce savings and investments, and the rate of economic and social advancement since a large proportion of the scarce resources are diverted towards consumption. Also, an increasingly larger number of persons continue to enter the working ages swelling the ranks of the unemployed. Before the beginning of the First Five-Year Plan an estimated three and a half million persons were unemployed in India. At the end of the Third Five-Year Plan, their number increased to ten million even though thirty-one million additional jobs were created during the three plan periods. The present age structure is also conducive to higher population growth as bigger cohorts of males and females continue entering reproductive ages, especially since universal and early marriage is the pattern in India. This would tend to further aggravate the unemployment problem.

 

The age structure of India’s population for the 1981 Census, when compared with that of the 1971 Census, reveals that it has changed slightly and has become “older”. The change is noticed specially in the age groups 0-9, 10-19 and 45 and above. In the age group 0-9, the proportion declined due to the decline in the level of the birh rate. The quantum of decline is higher in the age group 5-9, which suggests that fertility decline may be greater in the second half of the last decade compared to that in the first half. In the age group 10-19 and 45 years and above, the proportions have increased which indicates general improvement in the health conditions, specially in the young old ages.

 

Age-sex Pyramid

 

The age-sex structure of the population refers to the number of females and males in different age groups. A population pyramid is used to show the age-sex structure of the population.

 

The shape of the population pyramid reflects the characteristics of the population. The left side shows the percentage of males while the right side shows the percentage of females in each group. India: Age Composition -Adults, 58.7% Aged, 6.9% Children, 34.4% India.

 

Age structural dynamics includes fertility, mortality and as well as related changes in family planning and social arrangements. The use of age structure goes beyond demographic analysis to other important areas. Public polices aim to improve the welfare of a population; population welfare in turn is determined and shaped by the needs of present and future population; a population’s needs and its potential are strongly shaped by its demographic composition- i.e. by age-structural transition. In consideration of various uses of age data, information on age is routinely collected in every census and survey conducted in the country. Age misreporting remains a problem in the census. Certain segments of the population do not know their dates of birth so it ultimately leaves the enumerator to estimate the age to the likeliest age to be. In some cases the estimates could be several years off from their actual age.

 

Age composition by residence and broad age groups 0-14, 15-59 and 60+ for the year 2015 at the National level is shown in Table 1. The age group 0-14 is further sub categorized into the age groups 0-4, 5-9 and 10-14. It is observed that for most of the age groups, Male female differences in the age distribution of population are negligible except in the combined age group of 0-14, 15-59, 60+, 15-64 and 65+. In the age group 0-14, Male population is about one percent more than female, whereas in the age group 60+ as also 65+, percentage of female 0.6 and 0.5 percent more than Male. The proportion of Young children in the age group 0-4 and also the proportion of population in the age group 0-14 are higher in rural areas than in urban areas for both Male and Female. A higher proportion of Male and Female in the working age group 15-59 live in urban areas as compared to rural areas. Table 2 gives percentage distribution of estimated population by quinquennial age groups sex and residence for India and bigger States and UTs.

 

Table 1: Percentage distribution of Population by age groups to total population by sex and residence, India, 2015

Note: Total percentage may not add to 100 on account of rounding in broad age groups

Source : www.censusindia.gov.in/vital_statistics/srs_report/9chap%202%20-%202011.pdf

 

SEX COMPOSITION

 

Sex composition of the human population is one of the basic demographic characteristics, which is extremely vital for any meaningful demographic analysis. Changes in sex composition largely reflect the underlying socio-economic and cultural patterns of a society in different ways. Sex ratio defined here as the number of females per 1000 males in the population, is an important social indicator to measure the extent of prevailing equity between males and females in a society and influences directly the incidence of marriage, birth, migration, economic activities, etc. Development programmes may also have differential impact on male and female quality of life.

 

Sex Ratio

 

There are more males than females in India. This is mainly because of higher mortality experienced by the females than the males. The trend of the sex ratio, defined as the number of females per 1, 000 males, shows that upto the 1971 Census it was declining. However, in the 1981 Census it had slightly increased. The cause for the declining trend is attributed to the widening in the gap between the life expectancies of males and females. During the decade 1971-81, it appears that the death rate of females declined relatively more than that of the males. It is a common assumption that there are the same numbers of males and females at each age- actually, this is rarely the case. Migration, mortality, and fertility operate to create inequalities in the ratio of males to females (known as the sex ratio): Sex ratio= Number of males/Number of females*100

 

A sex ratio is greater than 100 thus means that there are more males than females, while a value of less than 100 indicates that there are more females than males. The ratio can obviously be calculated for the entire population or for specific age groups.

 

Fertility has the most predictable impact on the sex ratio because in virtually every known human society more boys are born than girls. Sex ratios at birth are typically between 104 and 110. The United States tends to be on the low end of that range and Asian societies tend to be on the high end, but the data do not permit many generalizations. Despite a great deal of research into the question of why the sex ratio is not simply 100, no one really knows (Clarke, 2000). This is perhaps a biological adaptation to compensate partially for the higher male death rates (or vice versa, since we are not sure why death rates are higher for males. In fact, data on miscarriages and fetal deaths suggest that more males are conceived than females, and that death rates are higher for males from the very moment of conception. Thus, some of the variability in the sex ratio at birth could be due to differences in fetal mortality. Mortality creates sex inequalities because at every age males have higher death rates than females. The cumulative effect of this is to produce a situation in which, as mortality declines, there are increasingly fewer males at the older ages than there are females. Western nations, having experienced the earliest declines in mortality, have thus become increasingly characterized by having substantially more older females than males. This seems to be an inevitable shift inherent in the demographic transition. On the other hand, migration offers a way to alter the biologically driven component of the sex ratio. In some instances, females are more likely to migrate (and thus to be added to or subtracted from a specific age group). In other situations, males are more likely to be the migrants and thus also to produce changes in the sex ratio that trump those created by the combination of the sex ratio at birth and the mortality differential by sex.

 

Measuring the Dynamics of the Age Transition

 

A population is considered old or young depending on the proportion of people at different ages. In general, a population with about 35 percent or more of its people under age 15 is “young,” and a population with about 12 percent or more of its people aged 65 or older can be considered “old.” Further, as the proportion of young people increases relative to the total, we speak of the population as growing younger. Conversely, an aging population is one in which the proportion of older people is increasing relative to the total. We can graphically visualize the age structure by constructing an age pyramid. We quantify the age structure in three major ways, by calculating the average age of a population, the dependency ratio, and the growth rates by age. Although we can compare these measures over two or more time periods to get a sense of trends, demographers have worked out more detailed ways of modeling the dynamics of age structure changes, and these include stable and stationary populations and computing population projections.

 

Population Pyramids

 

A population pyramid (or age pyramid) is a graphic representation of the distribution of a population by age and sex. It can graph either the total number of people at each age or the percentage of people at each age. It is called a pyramid because the “classic” picture is of a high mortality society (which characterized most of the world until only a several decades ago) with a broad base built of numerous births, rapidly tapering to the top (the older ages) because of high death rates in combination with the high birth rate.

Source:www.censusindia.gov.in/vital_statistics/srs_report/9chap%202%20-%202011.pdf

 

Average age and Dependency Ratio

 

Although a picture may be worth a thousand words, there are times when we like to summarize an age structure in only a few short words or, even better, in a few numbers. The average age and dependency ratio are two measures to help us do just that. The average age in a population is generally calculated as the median, which measures the age above which is found half of the population and below which is the other half.

 

An index commonly used to measure the social and economic impact of different age structures is the dependency ratio- the ratio of the dependent – age population (the young and the old) to the working-age population. The higher this ratio is, the more people each potential worker is having to support; conversely, the lower it is, the fewer people there are dependent on each worker. For example: suppose that a population of 100 people had 45 members under age 15, 3 people 65 or older, and the rest of approximately economically active ages (15-64). This is the situation in Nigeria, one of the highest fertility nations in the world. Forty-eight percent of the population is of dependent age (0-14 and 65+) compared with the remaining 52 percent of working age. Thus, the dependency ratio is 48/52 0R 0.92, which means that there are 0.92 dependents per working age- person nearly one dependent for each person of working age, which is a fairly load, especially as in most societies we will not find everyone of working age actually working.

 

The dependency ratio does not capture all the intricacies of the age structure, but it is useful indicator of the burden (or lack thereof) that some age structure place on a population. For individuals with large families, the impact of a youthful age structure, for example, will be immediately apparent. But even for the childless or those with only a few children, the effect may be higher taxes to pay for schools, health facilities, and subsidized housing. For those in business (whether government or private), an age structure that includes numerous dependents may mean that workers are able to save less, having no spend it on families, while government taxes must go toward subsidizing food, housing, and education rather than to financing industry or economic infrastructure, such as roads, railways, and power and communication systems.

 

Growth Rates by Age

 

The population growth occurs by age, not really as an overall number. Increases in the average age tell us generally that the age structure is going through alterations, but we cannot tell for sure where those changes are occurring. This is important because the age-graded aspects of society that tell us that we should examine the growth rates by age if we are going to fully understand what is happening in a society.

 

The Age Transition

 

Premodern society will have high fertility, high mortality, and probably very little in or out migration. This is associated with a young population, whereas the end of the transition is associated with an older population characterized by low fertility, low mortality, and probably a moderate amount of migration. This transition from a younger to an older population progresses through some predictable stages, with reasonably predictable consequences for the fabric of social life.

 

Summary

 

The distribution of the population by sex and age is one of the most important demographic groupings. The study of the age and sex structure occupies an important place in demographic statistics. In the first place, indices of the population’s age and sex structure play an important part in the system of indices of the plan for the development of the economic and cultural life of our socialist society. They are used by planning agencies for assessing the attained level of development of the economy and culture of the nation and of its individual regions, for verifying the course of fulfillment of plans, as well as for current and long-term planning. These factors engender the need to have data on the changing distribution of the population by sex and age, as well as similar data calculated for the future.

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