Revision as of 20:44, 7 November 2009

In demographic literature, the term generation ¹ has been given a precise meaning and refers to a group of persons born within a specified period of time, generally taken as a calendar year. The term cohort ² denotes a group of persons who experience a certain event in a specified period of time: thus birth cohort is a synonym for generation in the sense of 116-1, a marriage cohort is a group of persons married within a defined period, etc. In demography as in genealogy the term generation ³ may also be used to denote the descendants of a group of persons who are themselves a generation in the sense of 116-1. Thus the children of a group of migrants are often referred to as the second generation ^9★. Occasionally we also use the expression third or fourth generation. Generations can be qualified according to their current age as, for example, the young and rising generation ^6★, the middle-aged generation ^7★ or the generation in the prime of life ^7★ and the older generation ^8★ while the age limits are often vague and therefore require clarification. Cohorts of people born during historical periods related to low birth rates (or high) can be referred as birth-dearth or low-birth-rate cohorts ^11★ (or high-birth-rate cohorts ^10★--more colloquially baby-boomers). Occasionally consideration is restricted to lines of descent through one sex only, thus a male generation ⁴ or paternal generation ⁴ are the sons of a generation of males, a female generation ⁵ or maternal generation ⁵ the daughters of a generation of females. These distinctions are normally used when the length of a generation or mean interval between successive generations is calculated. (cf. 713-1).

• 2. Cohort, n.: the term cohort analysis is used to denote a method of analyzing data, in which the experience of individual cohorts is studied throughout their lives, or other specified periods.
  For purposes of military service the number of men who become liable to conscription in a given year is sometimes called the class of that year. In the United States the same term is used for a group of students who complete their studies at a particular school or university in a particular year.

• 11. Because of the depletion of births during the First World war, particularly in France, the French term “classes creuses” is sometimes used in the literature.

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