The knowledge and know-how the Virtual Statistical System offers is presented at different levels. The highest level is the Activities and Themes level, which can be accessed through the main menu, and includes the textual information that can be accessed directly under each of the tabs of the many subheadings under Themes and Activities.

This information, which serves as an introduction to various topics, is however often only the tip of an iceberg. More important are the thousands of hyperlinks embedded in the VSS, which are the second level of the VSS. Many of those links refer to key documents. Other links take the user to sites of international organizations, which form the third VSS level. These websites are clearly the richest source of information about statistical methodology, classifications and standards. Without diminishing the importance of others, the website of the United Nations Statistics Division should be mentioned here, and in their own domains of statistics, the FAO, ILO, IMF, OECD, UNESCO and World Bank.

All these websites give access to documents and practical 'how to' tools in certain areas of statistics. This the fourth level of information. Country websites are also very valuable as they give access to practices in official statistics. Some country websites are extremely rich in metadata. Again, without ignoring others, Statistics Canada, the Australian Bureau of Statistics and the Scandinavian countries may be singled out as outstanding examples.

Web technology also enabled the addition of a Wiki element to the VSS, where individuals may add to or comment on the information provided. Clearly, Wiki contributions will have to be somehow moderated. Another point of concern related to web technology is the risk of broken links. A solution must be found to repair such links, which is one of the challenges for the near future.

Keywords: Virtual statistical system; VSS; Knowledge base; Metadata

Biography: Willem de Vries is a former Deputy Director-General of Statistics Netherlands and Deputy Director of the United Nations Statistics Division. He has extensive experience in technical cooperation in statistics in various parts of the world, including the former Soviet Union, the Middle East, Africa and the Caribbean. After his retirement in 2004 he has been working as an independent statistical consultant, particularly for the World Bank and the European Union.