Conducting a population census is a difficult and complex task, and involves investing great efforts and large fiscal expenditures. The preparations for censuses and their execution are characterized by a constant battle with many professional, organizational and administrative difficulties.

To date, traditional censuses have been conducted, in which enumerators went out to all the residents' homes and collected data from the entire population by the use of questionnaires. The greatest difficulty in this system is ensuring the public's cooperation, which is a basic condition for conducting the census successfully. The importance of this issue arose in past censuses conducted in this country and throughout the world, and arises today, as well.

In light of these difficulties, and the great demand for detailed, frequent demographic, social and economic data which the population census provides, the statistical institutions in various countries began to examine possible alternatives to the traditional census, which is based on collecting data from each resident of the country. The goal is to abolish, or significantly reduce, the dependence on filling in questionnaires, and to become based - as much as possible - on administrative data bases existing in the country.

Indeed, in recent years a trend has been identified throughout the world for a more intensive use of administrative data for official statistics. The causes are many: technological changes, especially in the field of computers; the expansion of administrative data bases found in various organizations; the availability of the information; etc. These changes have caused those who deal in statistics to reach the conclusion that it is possible, and beneficial, to make greater use of the information existing in administrative sources, and these trends have not skipped the population censuses.

The transition from traditional censuses to administrative censuses is occurring in many countries throughout the world, but it is accompanied by many difficulties and therefore is taking a long time. In order to conduct an administrative census there is a need for census data in administrative data bases, and links between these data bases. In addition, administrative files often have problems of overage or underage in records belonging to the census population, errors in entries and delays in updating the data. Also, definitions of variables and their classification is often different from the information required for the census. Therefore, using data bases requires planning, caution and recognizing its limitations.

In Israel great strides have been made in using existing data bases for census purposes. The use of administrative files already began in the 1983 census, in which the Population Registry was used when going out into the field; and in the 1995 census, when the Population Registry was used for field work and for adding variables from it, as well as using data bases on income from work and allowances, which were added to the census data.

The integrated census is an additional step towards the growing use of existing data bases. The Improved Administrative File (IAF) is the basic file of the population census, which includes the framework of the census population, and is created by combining the Population Registry file with additional administrative files.

In addition, in order to provide the basic census information which also includes socio-economic data, other files from administrative sources will be used and added to the information collected in the population census.

Presently, the professionals at the Central Bureau of Statistics are diligently planning the future censuses of the State of Israel. These, as mentioned, will be based as much as possible on existing information which includes available administrative sources that can provide the framework for the census population, and the required data, together with directed field surveys and ongoing CBS surveys that will be used for conducting censuses.

Expanding the reliance on administrative files and existing data will enable the Bureau to conduct population censuses and provide the population with the required information more often and at a higher quality.