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Demographic composition of the population

Modified on 2015/05/22 08:48 by Sean Zheng Paths: Read in Order Categorized as Chapter 2 - Population, households and families
Table II.22

From gender issues to gender statistics on demographic composition of the population: illustrative examples

Policy-relevant questions Data needed Sources of data
Does the sex distribution of births suggest a prenatal sex selection? Live births by sex. Civil registration systems.
Population registers.
Household surveys.
Population censuses.
Are women or men of working age overrepresented in certain geographical areas, in urban areas or in rural areas? Population by sex, age, geographical areas and urban/rural areas. Population censuses.
Household surveys.
Population registers.
Are women overrepresented among older persons? Population by sex and age. Population censuses.
Household surveys.
Population registers.

  • + Gender issues
    • Several countries in the world have a ratio of boys to girls at birth significantly higher than expected, suggesting the practice of prenatal sex selection. Sex ratio at birth is determined primarily by biological factors. More boys than girls are born in all populations. The ratio usually varies between 103 and 107 boys to 100 girls (United Nations, 1998). However, in recent decades, there has been a rise in the ratio of boys to girls at birth in several countries, mostly located in Asia, suggesting prenatal sex selection to the disadvantage of girls (United Nations, 2010a). In countries with a high ratio of boys to girls at birth, the population groups more likely to practice prenatal sex selection consider sons to be much more valuable than girls, have relatively low fertility and contain a significant proportion of women with a level of access to technologies that allows them to know the sex of their foetus, making prenatal sex selection possible (UNFPA, Technical Division, 2010). Birth order, sex of previous children and total number of desired children are also important. For example, individuals who prefer to have sons are more likely to practice prenatal sex selection if they expect to have only one child or if only girls were born thus far in their family.

      Gender differences in migration and mortality shape the sex and age composition of active-age populations. Overall, women outnumber men in the older age categories (United Nations, 2010a). However, because of specific migration and mortality patterns, the overrepresentation of women at the national or subnational levels may start at earlier ages (United Nations, 2010a). More working-age women than men may live in rural areas or in certain regions of a country. In some countries, men are more likely than women to migrate temporarily from rural to urban areas or from one region to another for work (United Nations, 2000, 2008). Men may also be more likely than women to migrate to other countries, although, lately, geographical patterns of female and male migration have become more similar (United Nations, 2010a).

      Significant sex differences in adult mortality may also contribute to the overrepresentation of women below the age of 60. Overall, at the same age, men have a higher mortality rate than women, owing mainly to biological factors. In some countries, the gender gap to the disadvantage of men is larger because social factors such as occupational risks, heavy drinking and smoking, war and conflicts affect the survival of men more than that of women (United Nations, 2010a). In other countries, however, a number of factors that increase the vulnerability of women to infectious diseases or higher levels of maternal mortality may counterbalance the women’s biological advantage and reduce the gender gap in mortality (WHO, 2009).

      Since women live longer than men, they outnumber men at older ages. This imbalance increases rapidly with age. Older ages are associated with changes in marital status, living arrangements, wealth and health status that may affect women and men in different ways. Older women are more likely than older men to be widowed or divorced (United Nations, 2009). In developed countries, older women are more likely than older men to live by themselves in one-person households, to have lower pensions and to be at higher risk of poverty (United Nations, 2002, 2005, 2010a). In developing countries, older women with no pension benefits have to continue working for income while taking care of their husbands or grandchildren (United Nations, 2002). Many old women and men, especially those with mental and physical impairments, become victims of abuse and violence (United Nations, 2002). Gender issues related to older ages are becoming more and more important as the share of older-age population in total population is increasing as a result of declining fertility and increasing life expectancy, a phenomenon called population ageing. This phenomenon began in the more developed regions but is now taking place in the less developed regions as well.

  • + Data needed
    • Data needed to analyse demographic composition of the population are:

      (a) Live births by sex;

      (b) Population by sex and age.

      Additional breakdowns commonly considered for the data above are urban/rural areas, geographical areas, migration status and ethnicity.

  • + Sources of data
    • Population censuses are used to collect data on the sex and age characteristics of all individuals. These data can be used to estimate the demographic composition of various groups of population at the time of the census. For population estimates in between censuses, these data need to be combined with data on births, deaths and migration by sex and age collected either during the population census or from other sources. Data on the sex and age of young children (under the age of 1 or under the age of 5, for example) from population censuses may be used to estimate female and male births, provided sex-disaggregated data on infant and child mortality is available. In any case, the sex and age structure of the young population as provided by censuses can be used to assess the quality of data on female and male births as provided by censuses or other sources of data. In countries lacking a timely and reliable system of vital statistics, population censuses are often used to collect data on recent births (in the past 12 months) by sex.

      Civil registration and vital statistics systems can provide data on live births by sex.

      Population registers can provide data on the composition of the population by sex and age.

      Household surveys can be used as a source of data on the sex distribution of the population in various age groups. Demographic and health surveys and fertility and family surveys may provide data on recent births (births in the past 12 months) or on retrospective birth histories over a longer time period.

  • + Conceptual and measurement issues
    • Female births may be more severely underreported than male births in countries where women have a lower status. Registration of vital events may be incomplete and selective by sex. Some household surveys or censuses may also suffer from sex bias in the reporting of recent live births. It is important that the quality of data on female and male births is assessed on the basis of multiple sources providing data on births by sex, on number of young children (children under the age of 1, under the age of 5 or under the age of 6 in cases where age heaping is suspected) by sex and age and on number of children ever born by sex of the child and age of the mother. It is also important that data from multiple sources and the quality of such data are analysed over time. In general, it is expected that data quality improves over time with a concurrent reduction of sex-biased reporting. When this is the case, a substantial increase in the ratio of boys to girls at birth, compared to past levels and the normal range, is indicative of some prenatal sex selection.

      Misinterpretation of sex ratio at birth may occur if sampling errors are not taken into account when analysing data based on surveys. A ratio of 112 boys to 100 girls, for example, may suggest prenatal sex-selection when the data are coming from a civil registration system that is considered complete; in the case of a survey based on a small sample, however, such a ratio may be well within the confidence interval for the standard number of 107 boys to 100 girls. Therefore, it is necessary for countries to calculate confidence intervals for survey data on sex ratio at birth.

      In some population censuses or surveys, female members of the household may be more likely to be underreported than male members. The recording of household members in population censuses and household surveys may be sex-biased, such as when the practice is to record first all the male members and then all the female members. In addition, some sex-selective underenumeration may occur in countries or groups of population where women have a lower status. While a common problem in reporting the members of a household is the omission of infants, in some countries girls may be more likely to be underreported than boys.

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