Demography: Describing the Population Composition

Sex Ratio

Compares the number of male individuals to the number of females in the population

Sex ratio = (Number of Males / Number of Females) x 100

Sex Ratio fORMULA

Sex Structure

Compares the sex ratio across different categories of another characteristic (e.g., urban-rural classification, age groups).

Median Age

The middlemost age in a numerically ordered set of observations (ages).

Population Pyramid

is a graphic form that effectively describes the age and sex composition of a population simultaneously. From this graph, one can describe not only the age and sex structure but also explain and describe demographic trends of the population in the past.

Life Expectancy at birth

is the average number of years an infant is expected to live under the mortality conditions for a given year. These figures are derived from life-table analyses and are usually calculated separately for males and females due to differing mortality rates.

Urban-rural distribution

Illustrates the proportion of people living in urban areas compared to rural areas.

Population density

Determines how congested a place is and has implications for the adequacy of basic health services.

Crowding Index

Describes the ease with which communicable diseases can be transmitted.

: Natural increase

is simply the difference between the number of births and the number of deaths that occurred in a specific population within a specified period, usually one year. Example: Number of births in 1992 (1,684,395) minus number of deaths in 1992 (319,579) equals 1,364,816 persons.

Inter-censal estimates

Population estimates made on any date intermediate to two censuses, taking the results of both censuses into account.

Postcensal estimates

Estimates of population size on any date in the past or during a current date following a census.

Projections

Population estimates made on any date following the last census for which no current reports are available

census of population

is defined as "the total process of collecting, compiling and publishing demographic, economic and social data pertaining, at a specified time or times, to all persons in a country or delimited territory".

census

It contains data useful in estimating or projecting population size during periods other than the census year.

• It provides necessary demographic data used in national planning

de jure method

Assigns individuals to the place of their usual residence, regardless of where they were actually enumerated during the census.

de facto method

Allocates people to the areas where they were physically present at the census date, regardless of where they usually live.

Vital registration systems

deal with the continuous recording of vital events such as births, deaths, stillbirths, marriages, adoptions, divorces, and annulments as they occur in the population.