glossary    * L *
Demographical and statistical terms Symbols
late foetal deaths
are foetal deaths of 28 or more completed weeks of gestation. Foetal deaths of unknown gestational age are included with those 28 or more weeks.
late foetal-death ratios
are the annual number of late foetal-deaths per 1000 live births in the same year.
legal abortion
when the abortion occurs in conformity with the laws of certain countries.
legitimate birth
may be defined as one whose father and mother were married to one another at the time of conception. An illegitimate child or child born out wedlock may be legitimized or legitimated by the subsequent marriage of its parents.
legitimate birth rates
are calculated with legitimate births in the numerator and the currently married female population in the denominator.
life table
describes the course of mortality throughout the life cicle. Genarally a life table contains: the death rate among persons of a given age x; the probability of dying within a given age interval; the number of survivors to a specific age from an assumed initial number of births; the number of years lived collectively by those survivors within the given age interval; the person years lived by a hypothetical cohort from age x on onward; and the expectation of life of an individual of given age.
life table survival ratios
these ratios are derived from the L x column (stationary population) of the life table. They are simply the ratio of the number of persons in the stationary population that would be alive at a certain age to the number of persons alive at an earlier age.
life-time abortion rate
is the sum of age-specific abortion rates and is a synthtic measure of abortion per woman or per 1000 women.
live birth
is the complete expulsion or extraction from its mother of a product of conception, irrespective of the duration of pregnancy, which after such separation breathes or shows any other evidence of life such as beating of the heart, pulsation of the umbelical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placente is attached; each product of such a birth is considered live-born regardless of gestational age.
logistic population
is a population growing in accordance with the logistic law of growth, ie., a population in which the growth rate decreases as a linear function of the population already alive and which will tend asymptotically to an upper limit.
long-term emigrants
are residents or persons who have resided continuosly in the country for more than one year, who are departing to take up residence abroad for more than one year.
logit of the probability of dying
is given by the logarithm of the rate between the probability of dying before reaching age x and the probability of surviving at age x. See also the meaning of symbols q(x) and p(x) under the letter P.

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