A general demographic equation is a starting population plus the change in population due to natural increase plus the change in population due to migration.
For general population, this would be equal to the total starting population plus (births minus deaths) plus (immigration minus emigration)..
The most commonly used ratio in demography is the sex ratio, which describes the number of men relative to the number of women (i.e. number of men divided by the number of women).
This can be done for the whole population, but is more commonly calculated for specific age groups..
The term rate is very widely used, but some indices called rates in demography are in fact ratios, proportions, or more complex measures.
Strictly speaking, a rate is a measure of change in a population over a specified time period (usually a year)..
Population ratios are used to describe the degree of balance between two elements of the population, e.g., Males vs. females, children versus women of reproductive age.
The ratio is normalized to refer to a standard unit of people, usually 100 persons..
A general demographic equation is a starting population plus the change in population due to natural increase plus the change in population due to migration.
For general population, this would be equal to the total starting population plus (births minus deaths) plus (immigration minus emigration)..
The population composition includes the sex ratio, the number of men for every hundred women, as well as the population pyramid, a picture of population distribution by sex and age ( Figure 20
5 ) Figure 205 This population pyramid shows the breakdown of the 2019 U
S population according to age and sex (Credit: Populationpyramid net)
