A Report on Demographic Data State of the Art
by Dimiter Philipov Senior Scientist Max-Planck illstitute for Demographic Research Rostock, Germany on behalf of the NESSIE Network

1. Sources of demographic data: -Population census
   • Vital statistics
   • Population register
   • Civil registration system -Surveys
     Surveys are the main source of scientific data In CEEC (Central and Eastern European Countries) there have been very few surveys, if any, during the last 10 years.
2. Fields of research and their data requirements -population size, fertility, family, morbidity, mortality, migration. Problems exist with data concerning family and migration, because their definitions are fuzzy. ill the case of family formation, it is cohabitation that causes some problems. When does it begin? In the case of migration, the definition should clearly distinguish any moves, such as visits or business trips, from real migration.
3. Data comparability. Most of the data in censuses and vital statistics are crudely comparable. Few data are finely comparable though. The Human Mortality Database developed at the Max-Planck Institute for Demographic Research is an example of a data base that uses vital statistics and population census data for finer comparability among countries.
   The Fertility and Family Surveys (FFS) are an example of a harmonised and coordinated data collection. It was initiated by the Population Activities Unit (PAU) at UN ECE, Geneva, and carried out during the 90s. One and the same core questionnaires was used for surveys in 23 countries. The data were gathered at PAU and distributed with the one and the same file format and structure.
4. Access to data sources. Access to population registers is diverse. ill some countries these data are strictly confidential; in other counties access is free provided the data are used in the statistical office where they are stored. Some countries may sell register data but the price is high. Survey data are subject to conventional problems such as confidentiality. Seemingly problems of accessibility are not as acute as in other social fields. Once anonymised, the data are usually available for scientific research.
5. Funding is a significant problem particularly for the CEEC. It is the reason for not having good quality surveys in these countries.
6. Non-response in demographic surveys is usually high in Western European countries but low in CEEC. Confidentiality fears exist. They are significant obstacles for census and surveys. Other fears: respondents do not want to let the interviewers enter their house.
7. Potential for data improvement. There is little potential in improving population census and vital statistics. Changes in these systems of data gathering are very expensive.

There is a significant potential in the improvement of surveys. The examples of GGS and PP A are relevant. GGS was initiated by P AU at UN ECE. It is based on the coordinated work of3 scientific institutions. A joint team of researchers works for the creation ofa core questionnaire; the creation of a unified contextual data base. It is supposed that the survey design will be analogous in the countries where the survey will be carried out. PP A is based on the co-ordination of a larger group of institutions and other scientific groups. They design a core questionnaire. Both GGS and PP A do not consider financial involvement. Thus the problem of funding remains.

Demographic questionnaires include a number of issues that are the topic of other social and economic surveys. Examples: income, economic status, values. For this purpose demographers include relevant questions from proper specialized surveys. For example, values are studied by incorporating questions from EVS. The problem is in that the specialized surveys rely on a detailed study of the topic of interest, while demographers must restrict that topic to a small number of questions. Hence the quality could be low. One way to ease the problem is to dispose with a bank of questionnaires where one could be able to find diverse approaches to one and the same topic. The creation of such a bank is easy and inexpensive.