Population size is the actual number of individuals in a population. Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. These are usually places with hostile environments e.g. Antarctica. Places which are densely populated are habitable environments e.g. Europe

1. Population Size
Population Density
Population Distribution
Population Composition
Population Ratios

2. Population sizeis the actual number of individuals in a population.

4. Population density is a measurement of the number of people in an
area. It is an average number. Population density is calculated by
dividing the number of people by area. Population density is usually
shown as the number of people per square kilometer.

12. Population distributionmeans the pattern of where people live.
World population distribution is uneven. Places which
are sparsely populated contain few people. Places which
are densely populated contain many people. Sparsely populated places
tend to be difficult places to live. These are usually places with hostile
environments e.g. Antarctica. Places which are densely populated are
habitable environments e.g. Europe.

13. Population Composition: The distribution within a group of people
of specified individual attributes such as sex, age, marital status,
education, religion, language and occupation etc
These data are often compared over time using population pyramids.

14.  Population Pyramid, also called an age pyramid or age picture
diagram, is a graphical illustration that shows the distribution of
various age groups in a population (typically that of a country or region
of the world), which forms the shape of a pyramid when the population
is growing.

15. The Dependency Ratio
The dependency ratio shows how reliant young and old people are on
the economically active population.
Dependency Ratio = Young Population (0 - 14) + Old Population (65+)
/ Population Aged 15-64
The Support Ratio
Support Ratio = Population (15 - 64) / Population (65+) + Population
(0 - 14)
The support ratio is the inverse of the dependency ratio

16. Juvenile Index
The juvenile index indicates the proportion of children to the rest of
population. The greater the index, the more the children there are:
Juvenile Index = Population (0 - 14) / Population (15+)
Old Age Index
The old age index indicates the proportion of old people to young
people(Economically active people). The higher the old age ratio the
greater the number of old people.
Old Age Index = Population (65+) / Population (15-64)