glossary * A *
Demographical and statistical terms  Symbols 
abortion is defined, with reference to the woman, as any interruption of pregnancy before 28 weeeks of gestation with a dead foetus. There are two major categories of abortion: spontaneous and induced. Induced abortions are those initiated by deliberate action undertaken with the intention of terminating pregnancy; all other abortions are considered as spontaneous. 

abortion rate is a measure of the frequency of abortion in a population during a given period, usually a year. Abortions may be related to the total population or to the number of women in the reproductive ages, and may be specific for age, parity or any other characteristic. 

abridged lifetable is one in which most functions are given only for certain pivotal ages, frequently spaced at five or tenyear intervals after infancy. It is a life table computed by age intervals of 5 or 10 years, instead of single years of age. The youngest intervals are usually specified as age> 01, 14. The oldest age interval is an open interval. 

absolute average difference
estimates the degree of fitting between observed and theoretical data. 
ISC 
abstinence abstinence from coitus, particularly periodic abstinence is often included among contraceptive or birth control method. 

adjusted rates rates which have been standardized for age and/or other compositional characteristics in order to make them comparable with each other. 

age and durationspecific divorce rates are given by the number of divorces of women (or men) aged x to x+n and married t to t+k years, divided by the persons years lived by the corresponding married population. 

agechild ratio defined as the ratio of the elderly (age 65 and older) to the population in younger ages (under age 15). 
IV or ACR 
age dependency ratio is the ratio of the young and the elderly to the adult population.  ID 
age distribution of a population when the distribution of a population is given by individual years of age. 

age groups represents the age distribution of a population, which may be fiveyear age groups, also called quinquennial age groups or broad age groups,such as 019 years, 2059 years, 60 years and over. 

age of maximum value of fertility rates age corresponding to the maximum value of a given agespecific fertility rates distribution. 
FXM 
age heaping tendency of some people to round their ages to numbers ending in zero or five or to report certain ages instead of others. Also known as "age preference " or "digit preference". 

age of maximum value of the resistance function age corresponding to the maximum value of resistance function. 
XM 
agepattern of fertility relative (proportionate) distribution of a set of agespecific fertility rates. It espressed the relative contribution of each age group to total fertility. 

agesex structure of a population the number or proportion of the total population which falls in each category of a crossclassification by sex and age (either single years or age groupings). 

agespecific death (mortality rate), see Central death
rate. 

agespecific divorce rate is given by the number of divorces of women (or men) aged x to x+n divided by the number of the person years lived by married women (or men) between ages x and x+n. The denominator may be also represented by the total number of the person years lived at age x to x+n by women or men. 

agespecific fertility rate rate calculated by relating births generated during a give period from a number of women of age x (or of age x,x+h) to the quantity of women living of age x (or in age x, x+h). 
f(x) or F(x) 
agespecific first marriage rate is given by the number of first marriages of women (or men) aged x to x+n in a given year divided by the person years of women (or men) aged x to x+n who are exposed to the "risk" of first marriage. As second kind, the denominator may be represented by the total number of person years lived by men or women aged x to x+n. 

agespecific first net migration rate is computed as the amount of net migration (difference between immigration and emigration) at a given age per 1000 of the midyear population at this age. 

agespecific first net migration rate is computed as the amount of net migration (difference between immigration and emigration) at a given age per 1000 of the midyear population at this age. 

agespecific probability of emigration the annual agespecific probability of emigration between exat age x and x+1 is computed as the number of emigrants at a given age during the year related to midyear population at age x, plus half of the deaths during the year at age x. 

agespecific remarriage rate is given by the total number of remarriages for persons aged x to x+n, divided by the total number of person years lived by divorced, plus the number of the widowed between age x to x+n. 

age standardization a procedure of adjustment of crude rates ( birth, death or other rates) designed to reduce the effect of differences in age structure when comparing rates. 

average annual rate of change the average per cent increase or decrease per annum required to account for observed numerical change in size between two dates. 

average family size is the number of children for couple. 

average parity is the mean number of children even born per woman. 
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