Population Analysis benefits from contributions from Population Geography and Demography. Both disciplines look at human population and the components of population change; however, the approach and emphasis does differ.

Demographics is a branch of Sociology and looks primarily at age and sex distribution in communities/societies, as well as births and deaths. It was not long ago that Demography Schools did not study migration.

When considering Population, Demographers and Sociologists, would use birth and death numbers over a time period, to add to and take away from the total population in order to calculate the total population at the end of the year. If the total population count differed from the calculation, the left over bit, referred to as a residual, was net migration.

• P2 = P1 + B - D + Residual
• where P1 is total population at time one;
• where P2 is total population at time two;
• where B is the number of births;
• where D is the number of deaths;
• where Residual is the number left over, where the change in total population not accounted for by births and deaths, made up of migration and counting error.

The left over bit, net migration, is made up of in-migration minus out-migration. Net migration alone can be very deceiving. Net migration can be zero (0) even though large portions of communities have moved out and have been replaced by the same number of people from other areas.

For example, in a town of 10,000 people, each year 100 young adults (18 to 25) could leave with no young adults moving in and instead 100 people over 65 move in and no one over 65 moves out. After 10 years the complexion of the town has changed considerably. Indeed in some towns attractive to retirees the dependency ratio has shifted steadily to as low as only 4 out of 10 people of working age. Net migration by single year of age can be near 0, thereby hiding large migrations. Here is a chart...

... of net migration by single year of age (5 and over), for Canada, between 2001 and 2006, from a presentation to the Chamber of Commerce. The age group that moves the most appears to move the least. With "in" and "out" migration numbers, the chart would show large numbers of young adults moving in and moving out. An easily accessible confirmation of the difference in migration age, is to look at the number of migrants moving from one province to another within Canada as seen in the Chart below.

By looking at net migration as a residual, important dynamics impacting communities can be missed. Population Geography takes into consideration both in-migration and out-migration by single year of age, or broad age groups, by sex; therefore, gross as well as net migration can be calculated. Such additional information can provide insight into the difference between communities with stable versus those with high turnover populations.

The old way of thinking about population change is still referred to by some demographers, and some official statistical agencies, such as BC Stats, still uses this method.

The lack of information on "in" and "out" migration by age and sex required such methods. With the improvement in the information from sources such as the census long form from Statistics Canada, more light can be cast on the dynamics of population change. Therefore, many Demographers have revised the residual method because of improved data; however, some Demographers prefer the old method. Indeed BC Stats was shown the benefit of the use of in and out migration, but chose not to purchased the data from Statistics Canada. The Population Analyst proved that Statistics Canada's data is better than BC Stats data. For example,

Population Geography is an integrationist discipline providing insight into human to human interaction in relation to human interaction with the environment. Population Geography provides the foundation for studies in Human Geography and benefits from sound quantitative methods. Human Geography is a part of the social sciences, which utilizes scientific methods to better understand human activity. Population Geography welcomes the ground truthing of theories to check for ecological fallacies.

Population Geographers begin with an examination of the components of population change including births and deaths, as well as migration in and out of areas, whether internationally, nationally, or within regions. The number of people by age and sex, the number of births and deaths, and the number of migrants in and out of an area by their age and sex, forms the basis upon which social and economic activity are examined.

Building on the discipline of Geography, Population Geographers utilize scale, both across time and space, (era and area), to move from general overviews to specifics. Geographers map variations in human activity with reference to variations over the surface of the earth, including population density, ecosystems, administrative boundaries etc.

To understand changes in population, Population Geographers consider changes of both social and economic activity in relation to place. Examples include studies in rural and urban interactions, as well as societal expansion and contraction phases.

Geographers look for patterns in space, to see whether distributions are concentrated, dispersed, patterned or random. Geographers focus on moments in time, taking snapshots of various levels of aggregated data. Animation of snap shots help in the analysis of possible patterns.

As an integrationist study, Geographers also consider human activity in relation to ideas, as well as structure in relation to processes. For example, how do ideas regarding over-population effect our behavior? When do people change values from desire for growth and expansion to sustainability. How did European ideas about nature and political philosophy change after first contact with the First Nations of North America? Population Geographers explore changes in the numbers of peoples as well as changing ideas.

Population Analysis, estimates and forecasts, provides the denominator for measures of social and economic activity and human impacts on the environment.Population Analysis benefits from both Demography and Population Geography. Population Analysis examines the components of population change as well as dependency ratios, attributes such as linguistic groups, the number of people involved in various economic sectors and levels of refinement, and social class etc.