Net reproduction rate in the context of "Demographics of Afghanistan"

Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the older, previous one in a given area. The United Nations Population Division defines sub-replacement fertility as any rate below approximately 2.1 children born per woman of childbearing age, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003. This can be "translated" as 2 children per woman to replace the parents, plus a "third of a child" to make up for the higher probability of males born and mortality prior to the end of a person's fertile life. In 2023, the global average fertility rate was around 2.2 children born per woman.

Replacement-level fertility in terms of the net reproduction rate (NRR) is exactly one, because the NRR takes both mortality rates and sex ratios at birth into account.

Sources disagree as to the current population of Eritrea, with some proposing numbers as low as 3.6 million and others as high as 6.7 million. Eritrea has never conducted an official government census.

The nation has nine recognized ethnic groups. Of these, the largest is the Tigrinya, who make up around 50% of the population; the Tigre people, who also speak Semitic languages, constitute around 30% of residents. Most of the rest of the population belong to other Afro-Asiatic-speaking communities of the Cushitic branch. Additionally, there are a number of Nilo-Saharan-speaking ethnic minorities and other smaller groups.

Rodents have been employed in biomedical experimentation from the 1650s. Rodent studies up to the early 19th century were mainly physiological or toxicological. The first rodent behavioral study was carried out in 1822, a purely observational study, while quantitative rodent behavioral testing began in the late 19th century. Currently, rodents are commonly used in animal testing for physiological, pathological and behavioral scientific studies, particularly mice and rats, but also guinea pigs, hamsters, gerbils and others. Mice are the most commonly used vertebrate species, due to their availability, size, low cost, ease of handling, and fast reproduction rate.

The gross reproduction rate (GRR) is the average number of daughters a woman would have if she survived all of her childbearing years, which is roughly to the age of 45, subject to the age-specific fertility rate and sex ratio at birth throughout that period. This rate is a measure of replacement fertility if mortality is not in the equation. It is often regarded as the extent to which the generation of daughters replaces the preceding generation of women. If the value is equal to one that indicates that women will replace themselves. If the value is more than one that indicates that the next generation of women will outnumber the current one. If the value is less than one that indicates that the next generation of women will be less numerous than the current one.

The gross reproduction rate is similar to the net reproduction rate (NRR), the average number of daughters a woman would have if she survived her lifetime subject to the age-specific fertility rate and mortality rate throughout that period.