General fertility rate: Difference between revisions
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Explicitly, the general fertility rate is stated as the ratio of the number of live births in a year for every 1000 women who are in their childbearing years during that year. | Explicitly, the general fertility rate is stated as the ratio of the number of live births in a year for every 1000 women who are in their childbearing years during that year. | ||
==Distinction between total fertility rate and general fertility rate== | |||
{{further|[[total fertility rate]], [[total fertility rate versus general fertility rate]]}} | |||
The reason TFR and GFR are different is because, whereas the TFR is the ''total'' of age-specific fertility rates and it weighs the birth cohort for each year with a weight of 1 per birth cohort, the GFR is the ''average'' of age-specific fertility rates weighted by the population sizes for the ages. | |||
TFR and GFR would be easily related in the following two cases: | |||
* All the age-specific fertility rates are the same. In this case, the GFR would equal all the equal age-specific fertility rate values, and the TFR would be the product of that value and the number of childbearing years. | |||
* The population size is the same for each age. In this case, the GFR would equal the average of the age-specific fertility rate values, and the TFR would be the sum of the age-specific fertility rate values. In this case again, the TFR would equal the product of the GFR and the number of childbearing years. | |||
Of course, neither case occurs in practice: there is considerable variation in the age structure of the female population (see the [[population pyramid]] for more), and considerable variation in the age-specific fertility rates. | |||
Revision as of 09:02, 27 November 2013
Definition
Conceptual definition
The general fertility rate of a population over a given time period measures the ratio of the number of live births over that time period to the number of women who are in their childbearing years during that time period, and also divides by the length of the period.
Standard operationalization
The general fertility rate is operationalized as follows:
- The time period is chosen as one year.
- Childbearing years is operationalized using the age range of either 15-44 or 15-49 (the convention varies). A convention needs to be set regarding the date on which the woman's age is measured within the time period of the year. CHECK THIS: The general convention is to look at women whose age on their birthday anniversary within the year is within the childbearing years age range.
- The ratio is scaled to a denominator of 1000.
Explicitly, the general fertility rate is stated as the ratio of the number of live births in a year for every 1000 women who are in their childbearing years during that year.
Distinction between total fertility rate and general fertility rate
Further information: total fertility rate, total fertility rate versus general fertility rate
The reason TFR and GFR are different is because, whereas the TFR is the total of age-specific fertility rates and it weighs the birth cohort for each year with a weight of 1 per birth cohort, the GFR is the average of age-specific fertility rates weighted by the population sizes for the ages.
TFR and GFR would be easily related in the following two cases:
- All the age-specific fertility rates are the same. In this case, the GFR would equal all the equal age-specific fertility rate values, and the TFR would be the product of that value and the number of childbearing years.
- The population size is the same for each age. In this case, the GFR would equal the average of the age-specific fertility rate values, and the TFR would be the sum of the age-specific fertility rate values. In this case again, the TFR would equal the product of the GFR and the number of childbearing years.
Of course, neither case occurs in practice: there is considerable variation in the age structure of the female population (see the population pyramid for more), and considerable variation in the age-specific fertility rates.