The tables presented in the topic of active population cover the total population for 31 countries (for more information on received tables and geographic coverage, see "2001 Census Round - Tables Received" in the Annex at the bottom of the page). The level of completeness of the tables depends largely on the availability of data at the respective national statistical institutes. There are four ways of collecting census data, namely: - the traditional method of using census questionnaires (exhaustive census); - the method of using registers and/or other administrative sources;
- a combination of registers and/or other administrative sources and
- surveys (complete enumerations or sample surveys).
Other methods (other mixed census or micro-census) can be used as well.
Details for the method employed by each country are provided in "2001 Census Method"in the Annex at the bottom of the page.
In the same table you can find the dates on which the census was carried out in each country.