Why are people measured by numbers

Population development

Old-age quotient: Number of people aged 60 and over per 100 people aged 20 to under 60. Instead of the age thresholds of 20/60, other thresholds such as 15/65 or 20/65 are occasionally used.

Conservation level of the birth rate: The birth rate that results in the same number of births and deaths over the long term at a certain level of mortality, so that the population (excluding migration) is constant.

Population balance: Example of a population balance: Population on December 31, 2010 = population on December 31, 2009 plus the number of live births minus the number of deaths plus the number of immigrants from abroad minus the number of emigrations abroad (in each case in the course of 2010).

Demographic aging: Increase in the average age of a population, measured by the old-age quotient or the median age.

Dynamic of population development: If a population has a young age structure, this can lead to decades of (albeit not permanent) population growth due to excess birth rates, even though fertility has already fallen below the maintenance level. Conversely, the population may continue to shrink temporarily even if the birth rate increases from a low value to above the conservation level. The influence of the age structure on the growth or shrinkage of the population is also referred to by the terms "momentum" and "sluggishness" of the population.

Fertility: Reproductive behavior of a population. The fertility rates such as the total birth rate (see there) and the year-specific or generation-specific birth rate are used to measure fertility.
Births: The term "births" is mostly used as an abbreviation for "number of live births". As a result of multiple births, the number of live births is greater than the number of births.

Birth balance: Difference between the number of live births and the number of deaths in a certain period (usually calendar year). If the difference is positive (negative), we speak of a birth surplus (deficit).

(Raw) birth rate (rate) and age-specific birth rate: In German, the quotient "live births per 1000 inhabitants" is referred to as "raw birth rate" or "raw birth rate". If this is broken down into the individual years of childbearing age (15-45), the result is 31 "age-specific fertility rates" (live births per woman at a certain age for 1000 women of this age).

generative behavior: The totality of all economic, social, cultural, psychological and legal conditions for action and behavior, including the goals and values ​​of the people who influence fertility, measured by the number of live births per woman / man.

Youth quotient: Number of under 20-year-olds per 100 people aged 20 to under 60. Instead of the 20/60 age thresholds, other thresholds such as 15/65 or 20/65 are also used.

Cohort: Mostly synonymous with the year of birth (cohort of the year of birth). In addition, a distinction is made between marriage cohorts (total number of people who got married in the same year) and other cohort terms.

Life expectancy: Average lifespan in years, whereby the "life expectancy of a newborn" is differentiated from the "further life expectancy" for people of a certain age.

Median age: Each population can be divided into a younger and an older half according to age; the age at which they are divided is known as the "median age".

Migration: Change in the number and composition of a population in a certain area due to immigration and emigration from abroad (external migration) or from other regions of the same country (internal migration).

Migration background: Persons with a migration background include all those who immigrated to what is now the territory of the Federal Republic of Germany after 1949 (German and foreign persons) as well as all foreigners born in Germany and their children born here, including those who have since become naturalized.

Mortality: level of mortality in a population. Mortality is measured using various demographic indicators, for example the (raw) death rate (see there), age- and gender-specific death rates (or rates) and life expectancy.

Net Reproduction Rate (NRR): The net reproduction rate measures the extent to which a generation of women or parents is replaced by their offspring (without migration). It can be calculated as the number of girls born with a certain level of mortality per woman. If the NRR is greater than 1, the population is growing, if it is less than 1, it falls, and if the value is 1, the population is constant. The gross reproduction rate (BRR) does not take into account the influence of mortality on the number of births. When mortality is high, the difference between the BRR and the NRR is large.

Sexual proportion: Number of male residents per 100 female residents. The sexual proportion at birth is around 106 boys for 100 girls.

Support quotient: Sum of old age and youth quotient.

(Raw) death rate (rate): The death rate or rate is defined analogously to the (raw) birth rate (or rate) as the number of deaths per 1000 inhabitants. Breaking down the numerator and denominator of the death rate according to age and gender results in the "age- and gender-specific death rates (or numbers)".

Population growth rate: Change in population in a year as a percentage of the population at the beginning of the year. With a constant growth rate the population growth is "geometric" or "exponential", with an increasing growth rate "hypergeometric".

Migration balance (or balance): Difference between the number of immigration and emigration in a certain period (usually calendar year).

Migration rate: Similar to the birth rate, the influx rate (number) is defined as the number of immigrants per 1000 inhabitants. Accordingly, the emigration rate is to be understood as the number of emigrations per 1000 inhabitants.

Summarized fertility rate (rate): (English: Total Fertility Rate-TFR) measures the number of live births per woman or per 1000 women, whereby the influence of the age structure on the number of births is eliminated by having an equally large group at each age from 15 to 45 ("childbearing age") out of 1000 women. The TFR can be calculated as the sum of the age-specific fertility rates from 15 to 45. It indicates how many births per woman are absent if an equally large group of 1000 women passed the childbearing age of 15 to 45 in a single calendar year and the age-specific fertility rates for that year would apply.