MPIDR Technical Report

An "R" package for the production of a Lexis database of fertility data

Abstract

This technical report introduces software developed within the framework of the Human Fertility Database (HFD). The data on births provided by Statistical Offices are often classified only by calendar year and age of the mother or by calendar year and birth cohort of mother. For some countries and calendar years, birth data are available by five-year age intervals only. They may show broader or narrower ranges of available ages, they may include births with unknown age of the mother or unknown birth order, or they may show total births instead of live births. As part of the HFD project, a standardised methodology has been developed for the transformation of any set of raw data into data classified by single years of age and birth cohort, and (whenever possible) by birth orders Births with unknown age of the mother are distributed proportionally according to the birth data where age of the mother is specified. Within each age, births with unknown birth order are distributed proportionally across known birth orders. Aggregated age groups are additionally split into single-year ages by means of spline interpolation. Birth orders higher than five are combined into birth order 5+. Within each age, births are additionally split by year of birth of the mother (if such information is not present in input data). This Technical Report describes software in the form of packages for the free statistical computing environment “R” which implement the HFD methods to perform this manipulation. Keywords: fertility, birth counts, splitting, spline interpolation, iterative proportional fitting, Human Fertility Database, R