In order to find out more about the characteristics of a group of people, households, enterprises etc., one can either conduct a census or a sample survey. In a census, data about all individual units (e.g. people or households) are collected in the population. In a survey, data are only collected for a sub-part of the population; this part is called a sample. These data are then used to estimate the characteristics of the whole population. In this case, it has to be ensured that the sample is representative of the population in question. For example, the proportion of people below the age of 18 or the proportion of women and men in the selected sample of households has to reflect the reality in the total population.
A database containing information on a complete group of units is called a register. A register needs to be updated continuously. One example is a register containing information about all businesses in a country; this is called a business register. It contains information on the name, address, employment, turnover, ownership etc. of the businesses in the country. Such a register can then be used as the basis for a census or for the selection of a representative sample for a survey.
- Video Croatian Bureau of Statistics Census of population, households and dwellings