Semakan pada 08:07, 3 Jun 2013

320

Struktur jantina¹ atau taburan jantina¹ bagi penduduk diukur melalui nisbah antara bilangan penduduk bagi salah satu jantina² kepada bilangan keseluruhan penduduk atau kebiasaannya kepada bilangan penduduk bagi jantina yang lain. Jantina lelaki selalunya digunakan sebagai pengangka apabila merujuk kepada kelelakian³ bagi penduduk. Kadaran kelelakian⁴ adalah kadaran bagi lelaki dalam keseluruhan bilangan penduduk. Nisbah jantina⁵ adalah nisbah bagi bilangan lelaki kepada bilangan perempuan; yang biasanya diterangkan dalam nilai indeks (132-7) cth. bilangan lelaki bagi setiap 100 perempuan.

321

Istilah lelaki¹ dan perempuan² biasanya digunakan dalam demografi bagi menggantikan lelaki¹ dan wanita² untuk merujuk kepada individu bagi kedua-dua jantina pada setiap kumpulan umur termasuk kanak-kanak (323-3).

322

Umur¹ adalah salah satu ciri asas bagi struktur penduduk. Umumnya dinyatakan dalam tahun, atau tahun dan bulan; bagi kes kanak-kanak yang terlalu kecil, ia mungkin dinyatakan dalam bulan dan hari, atau dalam tahun dan pecahan perpuluhan bagi tahun. Ahli demografi biasanya meringkaskan umur kepada nombor bagi tahun lengkap² dan ia dipanggil umur pada tarikh lahir lepas³. Kadangkala, statistik demografi merujuk kepada umur dicapai semasa sesuatu tahun⁴. Apabila pecahan bagi tahun hidup lengkap yang lepas dikira sebagai setahun, ia adalah umur pada tarikh lahir akan datang⁵. Umur yang dinyatakan⁶ atau umur yang dilaporkan⁶, dalam banci atau pendaftaran penting, selalunya dibundarkan kepada integer seterusnya terutamanya apabila tarikh lahir yang akan datang adalah hampir. Istilah umur tepat⁷ digunakan terutamanya dalam pengiraan jadual hayat untuk menandakan masa apabila seseorang individu mencapai hari lahir. Soalan-soalan banci terdiri sama ada umur, tarikh lahir, atau umur pada tarikh lahir lepas. Apabila ilmu mengenai umur adalah tidak meluas, kalendar sejarah⁸ akan digunakan untuk menganggarkan umur. Ini adalah senarai peristiwa yang tarikhnya diketahui yang berlaku sepanjang hidup responden.

323

Dalam demografi, istilah-istilah tertentu yang menggunakan bahasa harian digunakan untuk menandakan perbezaan stages of life¹ or an approximate range of years. At the beginning of life comes childhood². In general a child³ is a person who has not yet attained puberty (620-2). In the very early days of life, the child is called newborn⁴. A Templat:NewTextTerm is a child who has not yet been weaned from its mother. The term infant⁶ 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 children⁷, a school-age child⁸ is a child at an age at which it is customary to attend school.

324

Childhood is followed by adolescence¹ or youth¹ which starts at puberty < 620-2). The terms adolescents² or young persons³ are employed for men and women between childhood and adult age⁴. Those who have reached maturity⁴ are called adults⁵. Old age⁶ is frequently used to define the period of life during which most persons are retired. Persons above that age are called old people⁸, the aged⁸ or the elderly⁸.

• 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.

325

The age distribution of a population is either given by individual years of age¹ or by age groups², which may be five-year age groups³, also called quinquennial age groups³, or broad age groups⁴, such as 0-19 years, 20-59 years, 60 years and over. Occasionally a population’s age distribution⁶ or age structure⁶ is given by classifying the population by year of birth⁵. Graphically an age distribution may be represented by a population pyramid⁷ which is a histogram (155-8) showing the population by age and sex and so named because of its pyramidal shape.

326

The mean age¹ of a population is the average age of all its members, the median age² 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 aging³ of the population. An increase in the proportion of young people involves a rejuvenation⁴ of the population. An old population⁵ has a high proportion of old people, a young population⁶ 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 aging⁷ a population by applying survival probabilities (431-6) by age to determine the number of survivors at a later date.

327

Aging (326-3) of a population must also be distinguished from individual aging¹ or senescence¹, and from an increase in the duration of human life or increased longevity² which is the result of improved standards of living and of medical progress. An individual’s physiological age³ will depend on the state of his tissues and organs. In the case of children we speak of mental age⁴, 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 birth⁵. The ratio of mental to chronological age is called the intelligence quotient⁶ (often abbreviated to I.Q.).

* * *