INEbase / Fertility Survey 1999 / Methodology
Summary
Fertility Survey 1999. (Last methodological note. Acrobat File 80 kb.)
Technical survey form
The Fertility Survey of the National Institute of Statistics is an investigation directed at families carried out between November 1998 and February 1999.
It continues the series of this type of surveys that took place in 1977 and 1985.
The 1999 Survey follows United Nations recommendations and its main objective is to obtain information on the demographic characteristics of women at a fertile age (from 15 to 49 years old), on their social and family environment and on the factors that influence fertility.
The need to carry out a survey of this type is obvious taking into account the current Spanish demographic situation, which is characteriszed by a low birth rate that will not insure generational replacement and that is one of the factors which determines the aging of the population.
The Fertility Survey 1999 sample was 16,000 households belonging to 966 sections. A home questionnaire was completed by each household in the sample. There is also another extensive questionnaire with the data for women of a fertile age - from 15 to 49 years old - from which only one per household was selected. A total of 7,749 women within this age period were interviewed.
Participation in this survey is voluntary. The Data Protection Agency approved the questionnaries content. The information is anonymous and all INE personnel involved with the project are sworn to secrecy about the data.
The information was collected by means of personal interviews using laptops with the survey questionnaires programmed onto them. Women interviewed were given the opportunity to complete the information themselves on the computer.
The design of the survey is the same used by the INE for all surveys directed at families. The sample used in this case was three stage stratified during the first stage units (censal sections). The second stage units are the family households. The third stage are women from 15 to 49 years old (one per household). The sample was distributed by autonomous Communities in such a way that data can be obtained for each of them.
Ratio estimates were used, with the 31/12/1998 population projections as the auxiliary variable.
The main topics investigated in the survey are the following:
- Relation between number of children and other characteristics of the woman or of their partner (level of studies, religion, nationality, economic activity, etc.).
- Family size and characteristics of the household and the housing.
- Intention of bearing children.
- Process of formation and dissolution of stable relationships. Their influence on fertility.
- Birth control, contraceptive methods and their use.
- Sanitary assistance during pregnancy and fertile life.
Circulation of results
The main results (provisional) of the Fertility Survey 1999 were presented in December 1999. The definitive, more detailed results are published in December 2000.