What is population?

Population is about people, and the dwellings, locations and environments that people live in. Population can be defined in many ways, for example by age, ethnicity, type of housing, birthplace or location.
Population size
Population size can refer to the total number of people living within a defined area, or it can refer to a group of people from a defined area who have similar characteristics (eg children aged 0 to 4 years, people of Asian ethnicities, people who live in two-bedroom houses, people who live in Mangere or in the Southland region).
Population structure
The structure of a population describes the relative numbers of people with similar characteristics within a population, for example, age groups, sex, ethnicity. The structure of a population shows how the subgroups within it affect its composition and characteristics. For example, it shows the percentages making up the different age groups of the population.
Population structure changes over time as people age, but also because of births, deaths and migration. Changes to social, environmental and economic conditions can also influence population structure. For example, changes in migration reflect a number of these factors and have different effects on different age groups.
The interrelationship between population, society, economics and the environment defines a population’s future size and make-up.

Population distribution
Distribution of a population within a defined area can be an important factor to consider in planning and analysis work. For example, clusters of families in only some suburbs of a city could influence planning for future school placement.

Measuring population
Population can be measured in three ways: actual counts of people, estimates of changes in actual counts due to population growth from births, deaths and migration, and projections of changes to future numbers of inhabitants.

Defining population for analysis
Defining the population relevant to a particular situation is a fundamental first step in any policy development or planning exercise.
The next step is to ensure that the sources used to derive the required measures are as compatible with each other as possible.
For example, birth rates may be based on the actual number of births relative to the estimated number of women in child-bearing ages at the time. For this purpose it would be appropriate to use population estimates for the denominator used to derive birth rates, rather than other sources.