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Multilingual Demographic Dictionary, second unified edition, English volume


Multilingual Demographic Dictionary, second unified edition, English vol.
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Trend  (TREND)

When values of a demographic variable are available over time, a demographic time series 1 is obtained. It is sometimes possible to decompose a time series into a trend 2 around which there are fluctuations 3, variations 3, or deviations 3 (141-2). Where such fluctuations tend to recur after certain periods, usually several years, they are called cyclical fluctuations 4 or, more generally, period fluctuations 4. In demography the most common period for compiling data is a year, and the fluctuations in sub-periods of a year are called seasonal fluctuations 5. The fluctuations that remain after trend, cyclical, and seasonal fluctuations have been eliminated are called irregular fluctuations 6. They may be due to exceptional factors such as wartime mobilization, or sometimes they are chance fluctuations 7 or random fluctuations 7.

  • 3. In a general sense the term variation may be used to describe change in any value or set of values for a variable.
  • 4. Periodic, adj. - period, n. - periodicity, n. cyclical, adj. - cycle, n.
  • 7. Random, adj.: due to chance (cf. 161-1).