Sampling in vital statistics

Nastassia Bobrova

Economic Institute of NationalAcademy of Science

Minsk, Belarus

Abstract

The methodology of sample survey of household is given. The number of demographic sampling in Belarusis provided.

Sampling in vital statistics can be regular and irregular. Surveyed object can be household or certain population group (a person) for special purposes.

The sample survey of households (Income and Expenditures of Households Survey) is an important part of the regular operations of the National Statistical Committee of the Republic of Belarus. Itrepresents the major source of information on the socio-economic status of the Belorussian households. The resultsof the survey are widely used in thevarious economic estimations made by the Committee(for instance, in the calculation of the Gross Domestic Product (GDP)and its distribution, in the computation of theconsumer price index, in the System of National Accounts and the balance of agricultural production, etc.).

An Act of the Cabinet of Ministers of the Republic of Belarus #259 from the 23rd December, 1994 (“About the conduction of the sample survey of households”) provides the legal basis for the carrying out thissurvey.The Act assumes confidentiality of received information as well as a compensation given to the households for their participation in the survey (10% of the monthly minimum salary).

The elaboration and implementation of the survey were conducted under the supervision of the World Bank. Advisers from the Bank consulted and coordinated the staff of the household department on the issues of the overall design of the survey, methodological aspects of the sampling, the content of questionnaires and data processing.

The primary aims of the survey are:

  • To obtain reliable information for the evaluation of the quality of life of population;
  • To provide the Belorussian Government and other interested organizations with reliable information;
  • To create a computerized system for the collection and processing of the survey results.

The survey is conducted annually since January 1995. Each year a sample of about 6000 households is selected. Every household has an equal probability to be selected, and this allows extending the obtained results over all resident households. The survey covers all types of households with the exclusion of the institutionalized population (persons living in nursing homes, prisons, convents, military barracks, etc.).

The household survey is a continuous oneand assumes participationof a household on the voluntary basis. Selected households are free to refuse their participation in the survey. Besides, a household may leave the survey due to death of its member, a change of address and so on; no household might be replaced by a new one.

Contents and structure of the survey

The main principles of the surveyare:

  • to collect detailed income and expenditure data for a representative sample of households;
  • to use a relatively short recall period (due to the unstable economic situation and particularly, high inflation households might not be able to recall the exact amounts of income or expenses).

The survey is restricted to one calendar year and basically designed as a sequence of four quarterly interviews that cover an entire year for the same sample of households.

Main components of the survey are:

1. The baseline interview. It is designed to establish a first contact with a household, tocollect the information ona household and its members’ characteristics, and makean appointment for the next visits. Prior tothe interview, each household receives an official letter from the Committeewith a tentative date and time for the interviewer to visit the household.

2. Fourquarterly interviewswhich areconducted in April, July, October of the current year andJanuary of the following year. Each interview covers the household expenses and income for the previous three months. At the beginning of each quarter, a household receives so-called a “memory aid”usedto record the major expenses made during the quarter. The memory aid is used during thesubsequent quarterly interview.

3. Fourtwo-week diarieswhich a household receives every quarter. Each diary is used for the recording of the every day expenses on food and othernon-food items made by a household during 14 days.

The following principles were considered during the development of questionnaires:

  • The content of the questionnaires should correspond to the general structure of the survey;
  • The content of the questionnaires should be aimed at the collection of data necessary for the development of the social policies;
  • The questionnaires should be simple and understandable from the one hand but detailed and concrete from the other.

Regarding the occasional sample surveys in demographic statistics,there is a number of studies on population migration.One of the examples is the project “Analysis of the youth labour migration 2005-2006”, financed by the Belorussian State Fund of the Fundamental Research.

As a database for the analysis the legal documents on the problem of youth and migration in Belarus, statistical reports and the results of sample surveys were used.

The following types of questionnaire were used in the project:

  1. A questionnaire of a potential migrant. Interviews were conducted at working place or place of study.
  2. An individual questionnaire of a labour migrant. In addition to the general questions on migration, the questionnaire consisted of three separated parts:

-A set of questions for those working (hired) on the constant basis;

-A set of questions for those engaged in reconstruction work, construction of a house or summer residence;

-A set of questions for those engaged in trade.

The selection was conducted on the “snowball” basis.

3. The questionnaire of the labour out-migrant (youth summer labour migration). The interviews were conducted by the companies organizing this migration.

4. The questionnaire of the labour emigrant. The interviews were conducted by the companies organizing this migration.

5. In addition to that,there is an on-line questionnaire for those who left the country for work and have not returned on time.

In order to study the specifics of non-return youth migration,the joint group of researchers conducted a survey of the young people who moved to the USA for the summer vacation and did not returned to Belarus after the expiration of the issued visa. The survey was conducted within the framework of international project “Migration: theory, methods and the practice of the regulation of migration”. The method of “snowball” was chosen in the sample design.

In addition, the Scientific Institute of the Ministry of Labor of the Republic of Belarus conducted a study in 1998 on the potential of external labor migration, migration flows and ‘push’ and ‘pull’ factors.

The special sampling of border area was carried out by professor Shakhotska within the bound of International CIS project in 2002.

The author is researching special population group (migrants). Statistic registration doesn’t provide reliability of migration data. So now it is necessary to carry out sample survey of migrants because of their benefit. For example, the author’s sampling of the primary data sources on migrants at Statistics Department in Minskwas allowed to reveal a lot of problems with registration of migrants. As a result of this problems the database mobility of migrants isn’t qualitative. Nowadays only sampling can help tocorrect the number of migrant and to research the subjective data. The main purpose of our demographers today is sampling promotion to vital statistics.

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