Key Points

Population density measures the number of persons per unit area. The formula is $\text{Density} = \frac{\text{Total Population}}{\text{Total Area}}$. It is commonly expressed in persons per square kilometer ($\text{persons/km}^2$).

This measures the total increase in population over a specific period. It is calculated by subtracting the earlier population from the later population: $\text{Absolute Growth} = \text{Population}_{\text{later}} - \text{Population}_{\text{earlier}}$.

This is the rate of population increase expressed as a percentage per year. The formula is $\text{Annual Growth Rate (\%)} = \frac{\text{Absolute Increase in one year}}{\text{Base Population}} \times 100$.

The birth rate is the number of live births per thousand persons in a year. It is calculated as $\text{Birth Rate} = \frac{\text{Number of Live Births in a year}}{\text{Total Population}} \times 1000$.

The death rate is the number of deaths per thousand persons in a year. The formula is $\text{Death Rate} = \frac{\text{Number of Deaths in a year}}{\text{Total Population}} \times 1000$.

The natural increase of population is the difference between the birth rate and the death rate within a specific period. The formula is $\text{Natural Increase} = \text{Birth Rate} - \text{Death Rate}$.

Sex ratio is defined as the number of females per thousand males in a population. It is calculated using the formula: $\text{Sex Ratio} = \frac{\text{Number of Females}}{\text{Number of Males}} \times 1000$.

The dependency ratio compares the dependent population (ages below 15 and above 60) to the economically active population (ages 15-59). The formula is $\text{Dependency Ratio} = \frac{\text{Population (0-14) + Population (60+)}}{\text{Population (15-59)}} \times 100$.

To find what percentage of a larger population a subgroup represents, use the formula: $\text{Percentage Share} = \frac{\text{Population of Subgroup}}{\text{Total Population}} \times 100$.

This measure shows the proportion of the population living in urban areas. It is calculated as $\text{Urban Population \%} = \frac{\text{Total Urban Population}}{\text{Total Country Population}} \times 100$.

A pie chart represents parts of a whole, where the entire circle is $100\%$. The angle of each sector is proportional to its value, calculated as $\text{Sector Angle} = \frac{\text{Value of Component}}{\text{Total Value}} \times 360^\circ$.

Bar graphs use rectangular bars of uniform width to compare data across different categories. The height or length of each bar is directly proportional to the value it represents, allowing for easy visual comparison.

A census is an official, periodic count of a population. It serves as the primary source of raw demographic data used to calculate key statistics like population density, growth rates, and sex ratios.