Fertility, Mortality And Migration
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Main page Fertility, mortality and migration
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Related closely to population studies is demography. Demography is a narrower field compared to population studies. Demography is the mathematical modelling and statistical investigations of population. It does this by studying three factors which act upon the population - fertility, mortality and migration.
 Fertility measures the number of children for each woman Developing countries usually have large values of TFR, while developed countries have small values of TFR. Table 2 gives the values of TFR of some selected countries.
These three factors are combined to obtain the following formula
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Fertility
refers to the actual number of babies born. The common measure used is total fertility rate, or TFR. It is defined as the number of births per woman as she goes through the age specific fertility rates. However,a shorter description is the average number of children a woman can have. Fertility is different from fecundity, which is the number of births which a woman is capable of giving.
Mortality
refers to the number of deaths. A term of measurement for mortality is life expectancy at birth - it is a the number of years a newborn baby is expected to live.
Migration
refers to the number of people entering or leaving a country. When
there are more people leaving than entering a country,
there is net migration out of the country. Hence,
migration has a negative value. If, on the other hand, there are
more people entering than leaving a country, there is a net
migration into the country. Hence, migration has a
positive value.