Revision as of 16:16, 13 November 2006

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Demography ¹ is the scientific study of human populations primarily with respect to their size, their structure ² and their development; it takes into account the quantitative aspects of their general characteristics. In statistical terminology any collection of distinct elements may be called a population ³, a word that is synonymous with universe ³ . However, in demographic usage, the term population ⁴ refers to all of the inhabitants ⁵ of a given area, though on occasion it may be used for part of the inhabitants only [e.g., the school-age population (cf. 346-7), the marriageable population (cf. 514-2)]. Such groups are properly called sub-populations ⁶. The term population is often used to denote more specifically the size ⁷, i.e., the total number ⁷ of the aggregate referred to in no. 101-4.

• 1. Demography, n. - demographic, adj. - demographer, n.: a specialist in demography.
• 4. Population, n. - Note that this term may also be used adjectivally as a synonym for demographic, e.g., in population problems, population analysis, population studies.
• 5. Inhabitant, n. - inhabit, v.: to occupy as a place of settled residence.

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Certain sub-disciplines within demography have received special names reflecting their objectives or their methodology. Historical demography ¹ deals with populations of the past for which written records are available. In the absence of such sources, the study of ancient populations takes the name of paleo-demography ² . In descriptive demography ³ the numbers, geographical distribution, structure and change of human populations are described by means of population statistics ⁴ or demographic statistics ⁴ . The treatment of quantitative relations among demographic phenomena in abstraction from their association with other phenomena, is called theoretical demography ⁵ or pure demography ⁵ ; because of its resort to various mathematical methods, in practice it is identified with mathematical demography ⁶. A piece of research that applies the tools of demographic analysis (103-1) to an actual population is often called a demographic study ⁷ . All the preceding disciplines place a great emphasis on the numerical aspects of the phenomena, and are sometimes referred to as formal demography ⁹, when they apply only to the size and structure of the population. In contrast the broader term population studies ¹⁰ also includes the treatment of relations between demographic events and social, economic or other phenomena.

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Demographic analysis ¹ is that branch of formal demography which controls for the effect of population size and structure on demographic phenomena ² and isolates the effects of each demographic variable from that of the others. It also studies the relations between demographic variables and how they interact to form population structures. A distinction is made between cohort analysis ⁴ or generational analysis ⁴ which addresses itself to a well defined cohort (cf. 117-2) followed through time, and cross-sectional analysis ⁵ or period analysis ⁵ which focuses on the demographic phenomena that occur during a precise time interval (such as a calendar year) among several cohorts.

• 4. Cohort analysis is a form of longitudinal analysis which deals with aggregates of persons possessing the same characteristic. Panel analysis follows the same individuals case by case.

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The study of relations between demographic phenomena on one hand and economic and social phenomena on the other forms another branch of the subject. The terms economic demography ¹ and social demography ² have been used by some writers. Demography also deals with the study of population quality ³, This phrase may be used with reference to all sorts of social and personal characteristics. In a slightly different sense the term primarily refers to the distribution and transmission of hereditary characteristics (910-3) which are the subject of population genetics ⁴ . Human ecology ⁵ is the study of the distribution and organization of communities with attention to the operation of competitive and cooperative processes and has part of its subject matter in common with demography, as does biometry ⁶ or biometrics ⁶ which deals with the application of statistical methods to all forms of biological research.

• 4. Population genetics is distinct from human genetics, which deals with the transmission of inheritable characteristics in man: population genetics includes the study of the distribution and transmission of hereditary traits in plant, animal and human populations.
• 5. Ecology, n. - ecological, adj. - ecologist, n.: a specialist in ecology.
• 6. Biometry, n. - biometrics, n. - biometric, adj. - biometrician, n.: a specialist in biometry. The terms biostatistics, n. - biostatistical, adj. - and biostatistician, n. are frequently encountered and are synonymous with the terms given for biometry.

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Finally, there is the study of population theories ¹. This term should not be confused with theoretical demography (102-5). Population theories are designed to explain or predict the interaction between changes in population and economic, social, psychological or other factors; they include purely conceptual treatments. Population theories occasionally form the basis of population policy ² (cf. §930), which deals with measures designed to influence population changes.