What two things are demographic measures?
Course ObjectiveDevelop skills using simple demographic tools to guide planning decisions Show
Expected OutcomeAcquire skills to design a demographic profile examining past and present population characteristics for a given locale. The profile will aid in the understanding of changes in the total population, as well as changes in the composition of the population over time. The information may assist in the provision of services to different segments of the population such as children, elderly, and the working age population. Three types of tools will be introduced in Lesson 3:
3.1 Measures of Population ChangeA simple way of measuring population change is to examine changes in the total population from one time period to the next. Equation 31 shows the calculation for population changes over time Equation 31: Population Change Over Time The calculation for percent change between two time periods is shown in Equation 32. Using data from Table 31, the following example demonstrates the use of Equation 32. Equation 32: Calculating Percent Change, with Examples Presenting the Information To present population information, it is necessary to compare the data with another source of information. Selection of the second set of information is based on the geographic location of the area under study. For example, a comparison of the region of interest with other regions, and/or with the entire country, may be preferred. For district plans, population change can be compared with other districts, or with the region in which the district is located. A comparison allows the planner to understand if his/her region or district is growing slower or faster than another locale. Table 31 provides information on changes in the total size of the population over time for both the Greater Accra region and the entire country. The information may be used to determine if the total population size of the Greater Accra region is growing slower or faster than the entire country.
What Additional Information is Needed? Further analysis is needed to identify why growth is taking place. It is also necessary to identify which segments of the population are experiencing growth. Information on the location(s) where growth is occurring is also needed. Information on economic activities is needed to understand why growth is taking place. Once these data are collected, planners must determine if the current economic trends will continue in the future. If economic growth is expected to continue, you may assume that population growth will also continue. Planners also need to know among which segments of the population growth is taking place. For example,
Percent change can be calculated among age groups to determine where growth is occurring. It is possible that new immigrants, with young children, are moving into the region. Growth of families with young children has implications for services and infrastructure including education, jobs, health care, and transportation needs. Such information is needed to determine the need for new services and the expansion of existing services and infrastructure such as roads, water and electricity. Planners must also identify locations within a region where growth is taking place to determine the best location for new services and facilities:
Information on the census boundaries for each census taking is also needed. Changes in census boundaries can account for increases in population. Population Density Planners are interested in changes in population density, that is, the number of people occupying a given area or unit of land. Equation 33: Population Density In rural areas, where a high percentage of the population is engaged in farming activities, the population density tool allows planners to calculate the number of people that reside and/or work on a unit of land. In urban areas, it can be used as a measure of crowding. The land area is usually expressed as population per square miles or kilometers. Density measures can be applied to two census periods to observe changes overtime. The information can also be transferred to a map to observe geographic changes. Table 32 includes land area, total population, and calculated land densities for different regions of Ghana for the years 1984 and 2000.
Population density has increased in all regions of Ghana for this period. Accra, located in the Greater Accra region, experienced the largest increase. Changes in population density for this region could imply possible crowding in the city. Further analysis can be performed by calculating density rates for districts within the greater Accra region. Components of Population Growth Population change can also be expressed in terms of the components of demographic change. The components include:
Equation 34 allows planners to observe which components of demographic change are contributing to the growth or decline of a locale. Equation 34 Population Change Planners are also interested in how fast a locale is growing each year. This information allows them to adjust plans to meet current and future needs of services that the population uses such as water, electricity, and garbage collection. The annual rate of population growth can be calculated using Equation 35. Equation 35 The calculations used in Equation 35, are based on the exponential rate of growth, which follows the principle of compound interest. That is, the population is assumed to experience a constant rate of growth, repeated or maintained year after year, which produces larger and larger increments simply because the total population steadily becomes larger. Demographers use base 10 logarithms and the natural logarithm e in calculations of the annual rate of population growth. An example of the use of Equation 35 is shown below using 1984 and 2000 census data of the Greater Accra region (Table 31).
Example of Equation 35 Alternative example of the Annual Rate of Population Growth Equation Use the following alternative to the annual rate of population growth equation (Equation 35) when a spreadsheet program, or calculator with log functions is not available. This method is easy to use, but the result is not as accurate as the one in Equation 35. In planning, it is necessary to know how long it would take for a region, district, or city to double in population size. The Population Reference Bureau (PRB), based in the United States, provides a simple method to estimate doubling time. This equation is very useful for calculating the growth of rapidly growing areas such as large cities. Equation 37, developed by the PRB, is applied below to the annual rate of growth of the Greater Accra Region. Equation 36: Doubling Time for Greater Accra Region Results: It will take 15.8 years for the Greater Accra Region to double in population size. The region will grow as a result of inmigration and natural increase, that is births minus deaths. Uses for this Information Should services and the infrastructure be increased to meet the demands of new residents, in particular to the capital city of Accra? Or, should strategies and plans be developed to make rural areas and other urban areas more attractive to potential migrants? The Ghanian government's regional and national development plans should be used to determine strategies to deal with this expected increase in population. To fully understand the changes in the population, each component of population growth must be investigated separately. Planners must answer the following questions.
Demographers use rates and ratios to examine the separate components of demographic change, as well as changes in the composition of the population. For example, an examination of the birth rate, overtime, provides insights into the contribution of fertility to population growth. Another example is the use of migration rates. Migration rates provide information on the impact of migration on population growth. 3.2 Ratios and RatesRatios measure the size of the first population group A in terms of another population group B. This ratio is read as the number of units of A per 100 units of B. Demographers, in general, state ratios in terms ofper 100 or per 1,000 people. Several types of ratios will be discussed including:
Sex Ratio The sex ratio, shown in Equation 37, summarizes the sex composition of a given population  the number of males per 100 females within the same population of a given locale. Equation 37 Sex ratios can be calculated for an entire country, region, or district. Note:
Why Use the Sex Ratio? It is extremely difficult to record migration (population movements in and out of locales). Sex ratios, however, can be used to get insights on population movement. If the sex ratio is constructed by 5year age groups, it crudely indicates in or outmigration among age groups. In later years, the sex ratio crudely indicates mortality. In general, there are more males than females in the earlier years as there are typically more male births than female births. In rural areas, there tend to be more females, especially for communities that experience outmigration of men to urban areas. In cities with heavy inmigration, there tend to be more men than women who are in the working age groups. In later years, after age 55, there are usually more women than men as a result of higher deaths among men in their later years of life. Equation 37 There are 96.14 males per 100 females in Ghana. Table 33 shows sex ratios calculated by age groups for Ghana's Volta region.
Sex ratios from Table 33 indicate there are more males than females in the 519, 1014, and 1519 age groups. From ages 2085, there are more females than males in the region. It is possible that men aged 2059 have left the region for economic opportunities. The differences beyond age 60 can be due to both mortality and migration. The analysis has implications for the supply of labor in the region. In addition, it indicates that more women reside in the region than men, in the working age groups. AgedChild Ratio The agedchild ratio indicates whether or not a population is young or aging. Use this ratio if planning services for these two groups in the community. Equation 38 An example of the agedchild ratio for Ghana in 1984 is shown below. Example of Equation 38 In this example there are 8.91 elderly residents per 100 children in Ghana in 1984. For a quick exercise, calculate this ratio for two census periods to determine if a trend is taking place. This ratio, for example, is compared with that of the census data of 1970 in Ghana. Another
Example of Equation 38 This example indicates there are 7.75 elderly per 100 children in 1970. What do these ratios suggest? There is slight increase in the number of elderly in Ghana between the two census periods, 1984 and 1970. More services may be needed to meet the needs of a segment of the population that will have different health, housing and transportation needs than children. Age Dependency Ratio The age dependency ratio indicates the number of people who are viewed as being dependent versus those that are viewed to be in the "working age groups." Equation
39 The following examples use 1970 and 1984 census data taken for Ghana. Example of Equation 39 There were 96.18 dependents per 100 working age population in Ghana in 1984. Another Example of Equation 39 In 1970, there were 133.9 dependents per 100 working age population in Ghana. What Does the Data Imply?In Ghana, the age dependency ratio has decreased over the period from 1970 to 1984. In 1984, however, the country was supporting a large dependent population, mostly children who required educational and health facilities. The 2000 census data can be used to see if the dependency ratio continues to decline. In addition, it can be compared with the agedchild ratio to see if children continue to be the primary dependent population. ChildWoman Ratio The childwoman ratio crudely indicates fertility levels in an area and is used in areas where fertility data are not available. It is used to measure the incidence of childbearing among women in their reproductive years. It only provides information, however, on those children ages 04 who have survived. The advantage of this tool is that it can be calculated using only census or survey data. The calculation for the childwoman ratio as shown in Equation 310. Equation 310 The following examples use 1970 and 1984 census data for Ghana. Example of Equation 310: ChildWoman Ratio for Ghana, 1970 Another Example of Equation 310: ChildWoman Ratio for Ghana, 1984 The childwoman ratio for the two census periods show that the ratio of children ages 04 to women in their reproductive years is declining. This result roughly suggests that fertility is declining in the country. Calculating RatesA rate provides information on the frequency of a demographic event, such as a birth, death, or migration. Demographers express rates as crude, general, or specific. A crude rate measures the frequency of a vital event occurring in the total population. General rates, such as the general fertility rate, limit the event to those persons at risk of the event such as women in their reproductive ages (1549 years of age). Specific rates, such as the agespecific fertility rate, measure an event among a subset of the population at risk. The agespecific fertility rate measures fertility among women in specific age groups in their reproductive years. Several types of rate calculations will be discussed including:
Equation 311 provides the general form for a rate calculation. Equation 311 Crude Rates: Birth and Death Rates The crude birth rate, as shown in Equation 312, shows the frequency of births occurring among an entire population, while the crude death rate (equation not shown) shows the frequency of deaths for the total population. The crude death rate would include deaths in the numerator. Equation 312 Crude birth or death rates are usually calculated for a period of one year. The denominator is the population at midyear, the point roughly where half of the year's changes in population would have occurred. Techniques to calculate the midyear population can be found in Lesson 5: Estimating Population Size. Changes in the age structure can alter the values of crude rates. All individuals including men, children, and the elderly are part of the total population. To understand changes in birth rates, it is best to use rates that control for age and gender such as the general fertility rate or the agespecific fertility rate. The remainder of the discussion of rates will focus on fertility. Migration and death rates are discussed in Lessons 7 and 8. Why are planners interested in fertility levels? Birth rates and the age structure of the population are highly related to one another. When birth rates are high, youth tend to comprise a high percent of the population. As a result, plans and resources must focus on meeting the educational, health, housing, and recreational needs of children. A young population will also produce more births since the next generation of young women will enter their childbearing ages in the next decade. Resources must continue to focus on meeting the needs of children, even when birth rates decline. Planners must therefore study fertility measures and the impact on the age structure of the population for several points in time. General Fertility Rate The general fertility rate is a more refined method than the crude birth rate. It eliminates distortions that may arise due to:
The general fertility rate, shown in Equation 313, is used primarily to observe changes in births when planners have limited information. Equation 313 An example of the general fertility rate calculation is shown below. Example of Equation 313 AgeSpecific Fertility Rates Agespecific rates include the age of individuals in the calculation of rates for events such as births and deaths. Equation 314 presents the equation for the calculation of the agespecific fertility rate. Equation 314 An example of the agespecific fertility rate using data from Table 34 is shown below. Example of Equation 314: AgeSpecific Fertility Rate Among Women Ages 2024 The results show that there are 249.9 births per 1,000 women in that age group in that given year. Agespecific fertility rates are usually calculated for each age group provided that birth statistics are available by age of mother. Total Fertility Rate The total fertility rate indicates the average number of children that would be born to women during their lifetime, if the women conformed to the agespecific fertility rates. It provides insights into a country's fertility levels, as well as information on potential household size which has implications for housing needs of families. The total fertility rate is shown in Equation 315. Equation 315: Total Fertility Rate Table 34 provides data and examples for the calculation of both agespecific and total fertility rates.
Infant Mortality Rate The infant mortality rate is an important measure of the health and development of the infant population within a given locale. The infant mortality rate, as shown in Equation 317, is the number of deaths of infants under 1 year of age per 1,000 live births. Equation 316: Infant Mortality Rate Based on the 1998 Ghana Demographic and Health Survey, where information is presented on trends in infant mortality, the rate has declined from 99.6 per 1,000 live births in 1975, to 56.7 per 1,000 live births in 1998. This implies that more and more infants are surviving their first year of life. This infant mortality rate can also be compared with the underfive mortality rate, that is the total number of deaths to children under age 5 per 1,000 live births. Ghana is also experiencing declines in under age 5 mortality, from 187.2 per 1,000 births in 1975, to 107.6 per live births in 1998 (calculation not shown). This implies that more and more children are surviving in the country. These children will require health and educational services. These rates can also be used in evaluation plans, specifically, to assess the quality of health care for infants, young children, and pregnant mothers. ExercisesQuestions 31 and 32 Agespecific fertility rates can be calculated for several points in time to explore trends in fertility among age groups. Table 35 presents the different types of fertility rates that have been discussed up to this point. The table presents agespecific fertility rates, the total fertility rate, the general fertility rate, and the crude birth rate for Ghana for three points in time, 1988, 1993, and 1998. Question 31.
Question 32.
b) Which of the following fields of planning will declines in fertility impact the most?
Knowing the composition of a population helps planners determine both the current and future needs for services and demands on the region's infrastructure. The elements of population composition (or structure) include:
Of these elements, household type and size and the age and sex composition of the population guide decisions on community needs including housing, health care, education, and recreation. Household Structure Households consist of people who reside in different types of living arrangements as indicated below. A household may include:
Information on the composition of the household and household size is usually found in census information. This information can also be obtained from sample surveys that are based on the entire population. 3.3 Population CompositionPopulation PyramidsThe age and sex distribution of a population plays a major role in guiding decisions about the provision of services for different segments of that population. Planners have two simple tools to examine the age and sex distribution of a population:
A population pyramid, also known as a horizontal bar diagram, is a graphic tool used to study the age and sex composition of a population. Its bars represent age groups beginning with the youngest ages at the base of the pyramid and the oldest age groups at the top. Males are represented on the left side and females are on the right side of the diagram. The age scale can be down the center axis or to the right or left of the pyramid. In most cases, 5year age groups are used beginning with ages 04. Population pyramids can be represented in absolute numbers or in percentages. When constructing a pyramid based on percent distribution, the combined total of males and females should be used in calculating percentages for age groups among males and females. One should not use the total population size for males to develop the percentages for male age groups. The percent distribution of males and females should be based on the combined population of all males and all females. Population age pyramids may be used to:
Constructing a Population PyramidA population pyramid may be constructed with a spreadsheet program such as Microsoft Excel, or by hand with a ruler and graph paper. Instructions for constructing a population pyramid with a spreadsheet are included in Population Age Pyramid Construction and Data Acquisition. The following steps may be used to construct a population pyramid by hand. Table 36 provides data needed to construct a population age pyramid for the Volta Region of Ghana.
Step 1: Obtain census information for males and females by 5year age groups. Step 2: Draw 5 columns on a sheet of paper.
Step 3: Title column 4 % Males and column 5 % Females.
Step 4: Draw two lines on either graph paper or plain paper  a long horizontal line and a vertical line intersecting at the midpoint of the horizontal line.
Step 5: Next use a ruler to make the horizontal bars.
Reading a Population PyramidFertility levels influence the shape of the pyramid for early age groups. A pyramid with a large base among the lower bars, or at the bottom, tends to reflect high levels of births within the population. Pyramids of this nature call attention to the need to provide a range of services to age groups 014 such as schools, primary health care services, and recreational facilities such as soccer fields. In areas of heavy outmigration, pyramids tend to have smaller bars between the ages of 20–49. Cities, in particular, have large bars between the ages of 20–49 which reflect movement for jobs, education, and other opportunities. Heavy inmigration places tremendous demands on planners to provide housing, health care, schools, and basic infrastructure such as roads, electricity, and safe water to new residents. Reading Figure 31 Figure 31 shows the population pyramid for data from Table 36. Observe the impact of mortality by looking at the top of the pyramid among the 65+ age groups. The bars at the top of the pyramid tend to be the shortest and reflect deaths among the population. Figure 31: The base of the pyramid indicates that there is a large number of youth between the ages of 0–9 among males and females. More males than females are leaving the region in their working years, 20–55. The top of the pyramid shows the impact of mortality on those 65+ for males and females. The pyramid clearly justifies resources for youth in the region. It also shows the impact of outmigration on the labor supply in the region. Planners may wish to develop programs to maintain or expand economic activities to discourage outmigration. For a trend analysis, four pyramids should be constructed:
The four population pyramids will allow planners to observe changes over time in the age and sex distribution. The graphs can be used in part to justify the present and future allocation of resources to specific segments of the population. ExercisesQuestions 33 and 34 A planner is writing a development plan for a district. The planner must examine a range of rates, ratios and other measures to understand what is taking place. He/she is in the early stages of developing a demographic profile and has collected some information to start with. Help the planner think about additional information to add to the profile. Focus on how the information can guide planning decisions. Use the data in Table 37 for the following exercises.
Question 33. Question 34. 3.4 ConclusionLesson 3 introduced the tools and information suitable for creating a profile for a region, district, or, other locale. The lesson includes key demographic tools used to help guide planning decisions. Think about other types of populationrelated information to be included in plans and planning related documents. Selection of population information should be based on the ability to assist in:
Identify information that will help you establish goals and objectives, and estimate the need for future services and facilities such as the number of schools, teachers, health care clinics, housing, and water consumption, to name a few. You can also select population statistics that can help you evaluate your plans. If the goal is to reduce infant mortality rates, this rate can be used as an indicator or evidence of the success of a primary health care plan. A demographic profile should not be isolated in its own section of the plan. Present and discuss population information in all sections of the plan. For example, if revising a housing plan, discuss changes in the total fertility rate, changes in the age/sex distribution, and changes in household size both in the population section of the plan and in a discussion of projected housing needs. Fertility measures such as the total fertility rate provide information on the average number of children women will have during their reproductive years. If developing a plan on expanding educational services, include information on fertility rates since it determines future numbers of youth. The number of new schools, teachers, and teaching materials will be based on information on the present and future size of youth in the given population. Exercise AnswersAnswer Question 31 a) Crude birth rate e) Childwoman ratio Answer Question 32 It takes 1020 years before fertility declines require changes in local and regional planning efforts. The next generation of mothers has already been born and will add to the population once they enter their reproductive years. Planners need to continue focusing on meeting the needs of youth for the next decade. Declines in fertility will not, however, have an immediate impact on the need for services for youth. In the long term (within the next decade) several sectors of planning may be influenced by reductions in fertility. Declines in fertility have implications for primary education facilities. If there are fewer children in the future, then there will be less need of primary education facilities and teachers. Lower levels of fertility can also influence the provision of health care services for children and women in their reproductive years. Health planners may be able to reallocate resources to meet the health needs of different segments of the population. Declines in fertility also have implications for family size and consequently housing needs. Smaller families will require less shelter. Answer Question 33
Answer Question 34 Information Selection Select population information based upon its role in guiding planning decisions. For a better understanding of the residents' characteristics include:
Housing Needs To plan for housing needs, the following information is needed. Remember: Age and sex distributions can be used to develop population pyramids for several points in time.
Information on the age and sex distribution of a population is critical when planning for the housing needs of different segments of that population. Need to Know Planners need to know where growth is taking place within the district. They can calculate percent change for each subarea of the district and place the information on a map. The location of new or expanded services and infrastructure is determined by changes in the location of population. If migration information is available from census information or sample surveys, planners can assess population movements and the impact on the sectors of the development plan. This is not a complete list of answers. The intent of this exercise is to encourage thinking about the types of population information needed to guide planning decisions. ReferencesGeorge W. Barclay, Techniques of Population Analysis (New York: John Wiley and Sons, 1958) 16–55. Arthur Haupt and Thomas T. Kane, The Population Handbook (Washington. D.C: Population Reference Bureau, 1978). James C. Raymondo, Population Estimation and Projection (New York: Quorum, 1992) 107–108. More
What are two types of demographics?The field of demography can be divided into two general areas, basic or academic demography and applied demography.
What are the demographic measures?Demographic measures are questions that allow pollsters and other survey researchers to identify nonopinion characteristics of a respondent, such as age, race, and educational attainment.
What are the three demographic measures?Demographic Measurement: Nuptiality, Mortality, Migration, and Growth. This article presents the principal ways in which nuptiality, mortality, migration, and population growth are currently measured in demography.
What are 4 examples of demographics?A demographic refers to distinct characteristics of a population. Researchers use demographic analysis to analyze whole societies or just groups of people. Some examples of demographics are age, sex, education, nationality, ethnicity, or religion, to name a few.
