Demographic data are data output of demography which is the study dealing with the human population. Demographic data can be related to the Earth, the same as geographic data. Demographic Data usually represent geographical location, identification, or describe populations.

This field of science and research can be applied to anything about the dynamic nature of the human population including how it changes over time and what factors are affecting the changes. This study also covers aspects of human population such as the size, structure, distribution, spatial and temporal changes in response to birth, death, aging or migration.

Demographic data which are most commonly used include crude birth rate, general fertility rate, age-specific fertility rates, crude death rate, infant mortality rate, life expectancy, total fertility rate, gross reproduction rate and net reproduction ratio.

Demographic data can be used in analyzing certain patterns and trends related to human religion, nationality, education and ethnicity. These data are also the basis for certain branches of studies like sociology and economics.

Collection of demographic data can be broadly categorized into two methods: direct and indirect. Direct demographic data collection is the process of collecting data straight from statistics registries which are responsible for tracking all birth and death records and also records pertaining to marital status and migration.

Perhaps the most common and popular methods of direct collection of demographic data is the census. The census is commonly performed by a government agency and the methodology used is the individual or household enumeration.

The interval between two census surveys may vary depending on the government conducting. In some countries, a census survey is conducted once a year or once every two years and still others do census once every 10 years. Once all the data collected are in place, information can already derived from individuals and households.

The indirect method of demographic data collection may involve only certain people or informants in trying to get data for the entire population. For instance, one of the indirect demographic data methods is the sister method. In this method, a researchers only asks all the women on the number of their sisters who have died or have had children who have died at what age they died.

From the collected data, the researchers will draw their analysis and conclusions based on indirect estimates on birth and death rates and then apply some mathematical formula so they can estimate trends representing the while population. Other indirect methods of demographic data collection may be to collect existing data from various organizations who have done a research survey and collate these data sources in order to determine trends and patterns.

There are a lot of ways for demographic methods for modeling population processes. Some of these models are population projections (Lee Carter, the Leslie Matrix), population momentum (Keyfitz), fertility (Hernes model, Coale-Trussell models, parity progression ratios), marriage (Singulate Mean at Marriage, Page model) and disability (Sullivan’s method, multistate life tables).

With today’s advancement in information technology and the mass development of computers which has caused the dramatic decrease in the price, many agencies are now employing the services of computer information systems to process demographic data into meaningful, useful and relevant information than can made as basis for wise decisions.

In fact, it is now a lot easier to get demographic data that can cover the whole planet while data users can drill down deep into the database to get more demographic data pertaining to very specific geographical area. With the popularity of the internet, looking for demographic data with corresponding analyses has become a lot easier and faster.