Population structure

Apart from the total size, the most important demographic characteristic of a population is its population structure. Population structure refers to the composition of the population in terms of age, sex, occupation, religion, ed- ucational status, geographical distribution, and socio-economic status. The structure of a population is influenced or affected by births, deaths, and mi- gration, and by their pre-disposing factors. The age structure of a population affects a nation’s key socio-economic issues. Countries with young popula- tions (high percentage under age 15) need to invest more in schools, while countries with older populations (high percentage age 65 and over) need to invest more in the health sector. The age structure can also be used to help predict potential political issues. For example, the rapid growth of a young adult population unable to find employment can lead to unrest (CIA 2014). The age–sex structure determines potential for future growth of specific age groups, as well as of the total population. For this reason, the age structure has significant government policy implications. Table 6.2 shows the case of Tanzania’s population structure, where 44.6% of the population are at the age of 1–4 years old and 19.5% are at the age of 15–24 years old. In total, 64.1% of Tanzania’s population is between the age of 0–4 and 15–24 years old. Planners need to understand the policy implications of such a popula- tion structure. As noted above, planning in a situation like this will require considerations of schools and jobs to accommodate the growing number of young population. A population of young people needs a sufficient number of schools and, later, jobs to accommodate them. Countries with a large pro- portion of older people must develop retirement systems and medical facili- ties to serve their aging population. Therefore, as a population ages its needs change—for instance, from childcare to schools, and from ‘childcare jobs’ to ‘elderly-care jobs’; it also requires change in types of housing and medical care. The type of education required to fulfil these needs calls for pro-active planning.

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Table 6.2

Tanzania’s popultion structure as per 2014 population estimates

Age group Male Female Total Total % 0-4 11,173,655 10,962,186 22,135,841 44.6 15-24 4,838,216 4,841,338 9,679,554 19.5 25-54 7,340,129 7,289,483 14,629,612 29.5 55-64 745,214 985,524 1,730,738 3.5 65 years and over 629,483 833,910 1,463,393 2.9 total 24,726,697 24,912,441 49,639,38 100 Source: CIA (2014)

6.4.2 Dependence ratio

Dependent people are usually those under the age of 15 and over the age of 64. The productive part of the population comprises the population between the ages of 15 and 64. Dependency is usually expressed as a percentage:

(number of people aged 0-14 and those aged 65 and over) (Total)Dependency ratio = _____________________________________________ x 100 (number of people aged 0 14 and those aged 65 and over) number op peple aged 15-64

As the ratio increases, there may be an increased burden on the productive part of the population to maintain the upbringing and pensions of the eco- nomically dependent. This results in direct impacts on financial expenditures on things such as social security, as well as many indirect consequences. The (total) dependency ratio can be broken down into the child dependency ratio and the aged dependency ratio (IOM 2008; APHEO 2011):

number of people aged 0-14

Child dependency ration = _____________________________ x 100

number of people 65 and over

Aged dependency ratio = _____________________________ x 100

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6.4.3 Population pyramid

Population pyramids illustrate graphically the effects of the three factors that influence population. The overall shape of the pyramid indicates the poten- tial for future growth. Population pyramids present the population of an area or country in terms of its composition by age and sex at a given point in time. The series of horizontal bars in a pyramid represent the percentage contri- butions of each age and sex group (often of 5-year age group intervals) in the population.

A glance at a population pyramid can tell a great deal about the population in question. One can easily see whether a population is young or old. By con- vention, males are shown on the left and females on the right, young persons at the bottom and elderly at the top of the pyramid (Figure 6.1). The ratio or percentage of the various age groups in a population determines the current reproductive status of the population and indicates what may be expected in the future. The shape of the pyramid reflects the major influences on births and deaths, plus any change due to migration over three or four generations preceding the date of the pyramid.

Figure 6.1

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6.5 Demographic transition

According to Thomas Malthus (1798), population growth should be limited, given the available scarce resources. So why is the world’s population grow- ing so rapidly in the regions with the fewest resources? In part, this puzzle can be explained by the demographic transition theory, which is a model de- scribing the transition from high birth and death rates to low birth and death rates that occurs as part of the economic development of a country. This transition can be broken down into five stages (Figure 6.2).

Stage 1: Countries have high birth and death rates.At this stage, both rates are high, the population grows slowly, and the population also tends to be very young: many people are born but few live very long. Reasons for high death rate are high incidence of disease, poor nutrition, famine, and poor lev- els of hygiene. Children are considered to be an economic benefit to families, reinforcing high birth rates. Children contribute to the household economy by carrying water and firewood, caring for their younger siblings, cleaning, cooking, and working in fields. With few educational opportunities, raising children costs little more than feeding them. As they become adults, children become major contributors to the family income and become the primary form of insurance for adults in old age.

Figure 6.2

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Stage 2: High birth rate but falling death rate.The total population begins to expand rapidly because of improved public health, better nutrition, and lower child mortality. At this stage, birth rates fall and eventually balance the lower death rates. Falling birth rates coincide with many other social and economic changes, such as better access to contraception, higher wages, ur- banization, commercialization of agriculture, a reduction in the value of chil- dren’s work, and greater parental investment in the education of children. Increasing female literacy and employment lower the uncritical acceptance of childbearing and motherhood as measures of the status of women. As birth rates fall, the age structure of the population changes again. Families have fewer children to support, decreasing the youth dependency ratio. But as people live longer, the population as a whole grows older, creating a higher rate of old-age dependency. During the period between the decline in youth dependency and rise in old-age dependency, there is a demographic window of opportunity called the demographic dividend: the population has fewer dependants (young and old) and a higher proportion of working-age adults, yielding increased economic growth. This phenomenon can further the cor- relation between demographic transition and economic development.

Stage 3: Falling birth rate and continuing falling death rate. The population growth slows down. Reasons for falling birth rate include preferences for smaller families (they cost less), changes in social trends and fashions, rise in materialism (e.g. one would rather spend money on expensive goods than pay for rearing more children), and lower infant mortality rate.

Stage 4: Low fluctuating, low birth rate, and low death rate.The population growth is small and fertility continues to fall. There are changes in personal life styles, and more women are in the work force; therefore fewer couples have children (they would rather advance their careers first).

Stage 5: Death rate slightly exceeds the birth rate.This stage, which is not depicted in Figure 6.2, causes population decline. This stage has been recog- nized only recently, and there are very few countries that are considered to be in Stage 5. Reasons for low birth rate include a rise in individualism, greater financial independence of women, lack of resources for future generations, and increase in non-traditional lifestyles.

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6.6 Population projection

Development plans are designed to cater for future needs of the present and future population. As a result, the importance of future population estimates for countries attempting to plan their economic and social development can- not be overemphasized. There are numerous possible methods for calculat- ing future population estimates. This section presents three of these methods which are considered useful for development planning (UN online).

Mathematical method. This method estimates the future size of a population by taking the number of individuals as determined at a more or less recent date in the past and by applying to it an assumed rate of increase, as a func- tion of time. The rate may be derived from observations on the past growth of the population itself or by analogy with rates observed in other populations in similar circumstances. The calculations can be carried out directly with reference to the net rate of population growth; or the assumed birth rates, death rates, and rates of immigration and emigration may be calculated sep- arately and added to obtain the rate of growth for each future period. The method is called ‘mathematical’ because emphasis is placed upon the for- mulation of equations to express the rates as functions of time, instead of on particular factors which may influence the trend during any specific period. Economic method: Population growth can seldom, if ever, be expected to be completely independent of changing economic circumstances. Mortality and fertility are responsive to economic conditions. The same is true of migration: immigrants are attracted to areas of economic opportunity, while emigrants depart from areas where opportunities are more restricted. A projection by the ‘economic’ method is most obviously appropriate for an area subject to easy, unrestricted in-migration and out-migration. For example, take a situa- tion where an important new industry is being established which will domi- nate the economy of an area. The assumed future capacity of this industry to absorb labour is then the primary determinant of population growth. To this amount of labour, a certain multiple must be added to represent dependants, as well as the additional workers in subsidiary industries (trade, services, etc.) who will be required in the expanding community.

Component method: The component method of population projection esti- mation is usually understood to consist in the separate projection of numbers of males and females in each age group of the population. Separate projec- tions for each of several ethnic or linguistic groups, for urban and rural pop- ulations, or for any other segments into which the population can be divided,

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may also be regarded as component projections. It is most convenient to pro- ject the population by time-intervals equal to the age-intervals into which the population has been divided. Thus, if the population is subdivided by 5-year groups of ages, the projection can most easily be made for 5-year intervals of time—that is, for the end of a 5-year period. Component projections of a population with respect to characteristics other than sex and age do not require any departure from the basic method. The procedures for the projec- tion of any one population segment can very well be identical to those for the projection of the combined population.

To conclude the presentation on projection methods, it is argued that instead of looking for increased technology, planners are advised to make good use of the existing technology for making population projections. Several soft- ware programmes exist at various costs. Recently, USAID, through its health policy initiative project, has launched a Spectrum Software which, among other facilities, may be useful for population project and planning purposes. This software can be accessed for free by searching online for ‘Spectrum’ (for detailed explanations of the software, one may wish to refer to http://data. unaids.org/pub/Manual/2007/demproj 2007en.pdf )

6.7 Integration of demography in development planning

There is a close relationship between population growth and development. In the short run, the effects of population growth may appear marginal, but such growth sets into motion a cumulative process whose adverse impact on various facets of development may turn out to be very significant in the medium and long terms. This is because population variables influence the development and the welfare of individuals, families, and communities at the micro level, and the district, region, and nation as a whole at the macro level. The effects and responses to population pressure interact at all these levels Rapid population growth in situations of low economic growth tends to in- crease outlays on consumption, drawing resources away from saving for pro- ductive investment, and, therefore, it tends to retard growth in national out- put through slow capital formation. The strains caused by rapid population growth are felt most acutely and visibly in the public budgets for health, edu- cation, and other human resource development sectors.

Population and development influence one another. The influence may be positive or negative, depending on other factors and conditions. In the case

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of Tanzania, the aforementioned demographic factors interact and create the following problems—at least in the short term:

1. The rapidly growing young population demands an increase in expendi-