Multilingual Demographic Dictionary, second unified edition, English volume
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The sex structure 1 or sex distribution 1 of the population is measured by the ratio of the total number of one sex 2 to the total number of the population or, more frequently, to the total number of the other sex. By convention, the male sex is usually considered in the numerator and we speak of the masculinity 3 of the population. The masculinity proportion 4 is the proportion of males in the total population. The sex ratio 5 is the ratio of the number of males to the number of females; it is usually expressed as an index value (132-7) i.e. the number of males per 100 females.
- 3. Occasionally, the numerator of this ratio relates to the female population, and the feminity of the population is measured.
The terms males 1 and females 2 are commonly used in demography in place of men 1 and women 2 to refer to persons of each sex at all ages including children (323-3). In a similar fashion the terms male child 3 and female child 4 replace boy 3 and girl 4.
Age 1 is another fundamental characteristic of population structure. Generally it is expressed in years, or years and months; in the case of very small children, it may be given in months and days, or in years and decimal fractions of years. Demographers usually truncate the age to the number of complete years 2 lived, and this is called age at last birthday 3. Occasionally demographic statistics refer to the age reached during the year 4. Where the fraction of the last complete year lived is counted as a whole year, as in some actuarial applications, we speak of age at next birthday 5. Stated age 6 or reported age 6, in a census or vital registration, is often rounded upward to the next integer especially when the next birthday is near. The term exact age 7 is used, particularly in life table calculations, to denote the time when an individual reaches his birthday. Census questions include either the date of birth, age at last birthday, or even simply age without further precision. When the knowledge of ages is not widespread, a historical calendar 8 may be used to estimate ages. This is a list of events with a known date that occurred during the lifetime of the respondents.
- 2. Thus, age groups (325-2) are usually expressed in completed years and the group aged 6-13 years includes the individuals whose exact ages (322-7) are comprised between 6 and 14 years.
In demography, certain terms which have been taken from everyday language are used to denote different stages of life 1 or an approximate range of years. At the beginning of life comes childhood 2. In general a child 3 is a person who has not yet attained puberty (620-2). In the very early days of life, the child is called newborn 4. A child at the breast 5* is a child who has not yet been weaned from its mother. The term infant 6 may be used to denote a child who has not reached its first birthday, though in colloquial language it may be applied to slightly older children. Children who have not yet reached the compulsory school age are called pre-school children 7, a school-age child 8 is a child at an age at which it is customary to attend school.
- 6. Infant, n. - infancy, n.: the period of being an infant - infantile, adj.
Childhood is followed by adolescence 1 or youth 1 which starts at puberty < 620-2). The terms adolescents 2 or young persons 3 are employed for men and women between childhood and adult age 4. Those who have reached maturity 4 are called adults 5. Old age 6 is frequently used to define the period of life during which most persons are retired. Persons above that age are called old people 8, the aged 8 or the elderly 8.
- 3. The term youth is also employed collectively. When used in the singular, it more frequently refers to a male. In the United States of America, teenager refers to persons in their teens, i.e., between 13 and 19 years.
- 4. Maturity, n. - mature, adj. - maturation, n.: the process of growing to maturity.
The age distribution of a population is either given by individual years of age 1 or by age groups 2, which may be five-year age groups 3, also called quinquennial age groups 3, or broad age groups 4, such as 0-19 years, 20-59 years, 60 years and over. Occasionally a population’s age distribution 6 or age structure 6 is given by classifying the population by year of birth 5. Graphically an age distribution may be represented by a population pyramid 7 which is a histogram (155-8) showing the population by age and sex and so named because of its pyramidal shape.
The mean age 1 of a population is the average age of all its members, the median age 2 is the age which divides the population into two numerically equal groups. When the proportion of old people in a population increases, we speak of the aging 3 of the population. An increase in the proportion of young people involves a rejuvenation 4 of the population. An old population 5 has a high proportion of old people, a young population 6 has a high proportion of young people or children. The term aging used above should not be confused with the technique used in population projection, which consists of aging 7 a population by applying survival probabilities (431-6) by age to determine the number of survivors at a later date.
- 3. Also written ageing.
- 4. The word younging is used by American demographers.
Aging (326-3) of a population must also be distinguished from individual aging 1 or senescence 1, and from an increase in the duration of human life or increased longevity 2 which is the result of improved standards of living and of medical progress. An individual’s physiological age 3 will depend on the state of his tissues and organs. In the case of children we speak of mental age 4, which is defined as the age at which the attainments of the individual child as measured by certain tests can be performed by the average child. In studies of mental and physiological age, a distinction is made between these ages and chronological age measured by the time elapsed since the individual’s date of birth 5. The ratio of mental to chronological age is called the intelligence quotient 6 (often abbreviated to I.Q.).
- 1. Senescence, n. - senescent, adj.
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