http://www.wisegeek.com/what-is-demography.htm

Ibn Khaldun (1332-1406) is regarded as the “father of demography” for his economic analysis of social organization which produced the first scientific and theoretical work on population, development, and group dynamics.

Edmond Halley, developed the life table as the basis for life insurance mathematics.

Thomas Malthus concluded that, if unchecked, populations would be subject to exponential growth.

Three processes of population change:

fertility

mortality

migration

Fertility involves the number of children that women have and is to be contrasted with fecundity (a woman’s childbearing potential)

Mortality is the study of the causes, consequences, and measurement of processes affecting death to members of the population.

Migration involves the movement of people from geographical area to another geographical area.

Demographics are used in the gathering and recording of statisitcs and data in health. Helps to determine future public health needs and concerns in realtaion to basic medical care thru the spread of disease and illness.

Hope some of this helps you.

formulas include:

Suppose that a country (or other entity) contains Populationt persons at time t. What is the size of the population at time t + 1 ?

Populationt + 1 = Populationt + Naturalincreaset + Netmigrationt

Natural increase from time t to t + 1:

Naturalincreaset = Birthst − Deathst

Net migration from time t to t + 1:

Netmigrationt = Immigrationt − Emigrationt