Population exponentialとは 意味・読み方・使い方

The ratio of total growth in a given period to the mean population of that period is called the growth rate ¹. Occasionally this rate is computed with the population at the beginning of the period rather than with the mean population as a denominator. When population increase over a period of more than one calendar year is studied, the mean annual rate of growth ² may be computed. In computing this rate it is sometimes assumed that the population is subjected to exponential growth ³ during the period, and time is treated as a continuous variable. The size of an exponential population ⁴ would grow as an exponential function of time. The exponential growth rate ⁵ is equal to the instantaneous rate of growth ⁵. The ratio of natural increase (701-7) to the average population during a period is called the crude rate of natural increase ⁶ and is equal to the difference between the crude birth rate and the crude death rate. The vital index ⁷ is the ratio of the number of births to the number of deaths during a period; this measure is no longer much used.

• 3. When time is treated as a discrete variable, reference is made to geometric growth.
• 4. This is occasionally called a Malthusian population, but the term is ambiguous in view of its sociological connotations (see 906-1).

More...