| The Human Fertility Database
Explanatory notes
On each country page, there are three blocks of data:
This block includes the following data:
-
Live birth counts for all birth orders combined and (whenever possible) by birth order by all Lexis shapes (Lexis triangles, squares, vertical and horizontal parallelograms).
-
Female population exposures by all types of Lexis shapes (Lexis triangles, squares, vertical and horizontal parallelograms).
-
Unconditional age-specific fertility rates for all birth orders combined and (whenever possible) by birth order by Lexis squares, vertical and horizontal parallelograms.
-
Summary indicators of period and cohort fertility, calculated on the basis of age- and (whenever possible) order-specific data by Lexis squares and horizontal parallelograms, respectively. These indicators include the total fertility rate, the total fertility rate by age 40, the mean age at birth, the mean age at birth by age 40, cumulative fertility rates, and parity progression ratios (for birth cohorts only).
Detailed explanations of the Lexis diagram and the Lexis shapes as well as a description of the calculation methods behind the displayed values are given in the HFD Methods Protocol.
This block includes the following data:
-
Cohort fertility tables, specific for age and parity dimensions.
-
Period fertility tables, specific for age and parity dimensions.
-
Census- or register-based fertility tables (age and parity dimensions).
-
Female population exposures by age and parity from the period fertility tables and/or from census- or register-based period fertility tables.
-
Conditional period fertility rates. These data are extracted from period fertility tables and/or census- or register-based fertility tables featured in this block.
-
Period table summary indicators. The table summary indicators include the table mean age at birth and the summary index of period fertility controlling for age and parity.
Cohort fertility tables comprise the following columns (functions):
|
Cohort
|
|
Mother's year of birth
|
|
x
|
|
Age at childbearing in completed years
|
|
i
|
|
Birth order of child (1-5+);
relates to parity i-1 (0-4+)
|
|
bi(x)
|
|
Table number of births of order i in age interval
[x, x+1)
|
|
li-1(x)
|
|
Table population (table cohort size) of parity i-1
by age x
|
|
qi(x)
|
|
Probability of having an ith birth in age interval
[x, x+1)
|
|
mi(x)
|
|
Conditional age-specific fertility rates (occurrence/exposure
rates) in age interval [x, x+1)
|
|
Sbi(x)
|
|
Cumulative (in respect to age) births of order
i by age x
|
|
chi(x)
|
|
Average number of children by age x
in the highest parity category i4+
|
Note that i is the birth order varying from 1 to 5+ that relates to parity i-1 varying from 0 to 4+.
Calculation of cohort fertility tables is described in the Methods Protocol. Information about formats of the respective data files can be found in the Data formats document.
Period fertility tables in the HFD include the following variables:
|
Year
|
|
Calendar year of occurrence of birth
|
|
x
|
|
Age at childbearing in completed years
|
|
wi-1(x)
|
|
Weight of parity i-1 in the total female population exposure in age interval [x, x+1)
|
|
mi(x)
|
|
Conditional age-specific fertility rates (occurrence/exposure
rates) in age interval [x, x+1)
|
|
qi(x)
|
|
Probability of giving an ith birth in age interval
[x, x+1)
|
|
li-1(x)
|
|
Table population (table cohort size) of parity i-1 by age x
|
|
bi(x)
|
|
Table number of births of order i in age interval [x, x+1)
|
|
Li-1(x)
|
|
Table population exposure of women of parity i-1 in age interval [x, x+1)
|
|
Sbi(x)
|
|
Cumulative (in respect to age) births of order i
by age x
|
Population weights of parity i-1, wi-1(x) are assessed in two ways depending on data availability.
-
For countries that have sufficiently long time series of order-specific period data on births, weights wi-1(x) are being reconstructed from the time series of period data by cumulating fertility of birth cohorts over their reproductive life span.
-
For countries where order-specific data on births are available for a short period only, population census or population register data are employed to derive the initial (for one starting year, 'base year') age-parity distribution of women. The selected census or register from which data are used is called the 'golden' census. In exceptional cases, data from a large-scale survey can be considered for the 'golden census'.
Census- or register-based period fertility tables include the same life table functions as the period fertility tables. In these life tables, however, the weights wi-1(x) are based on self-reported or officially estimated information on parity of women originating from censuses or population registers.
The census- or register-based period fertility tables are calculated for each census year for which suitable data are available. The population register data are treated the same way - the period tables are being computed for all years covered by the register.
Estimation of the population weights and period life tables are described in the Methods Protocol. Information about formats of the data files can be found in the Data formats document.
All input data used for the computation of output fertility indicators are provided on the country pages. These data include the originally collected raw country data that are converted into a standardized format (described in the Data formats document). For every country included in the HFD, four types of data files are provided, containing data on:
-
Births by calendar year, age of the mother, mother's year of birth, and (if available) birth order;
-
Age-parity specific distribution of female population (from population census, population register or large scale survey);
-
Births by calendar year and month;
-
Female population size by calendar year and age (for countries and periods not available in the HMD).
Additionally to the input data, there are two documents in pdf format. The first file contains Notes to specific numbers or parts of the input data. The second file contains References to the sources of the input data.
|