Therefore, since its twenty-ninth session in February 1997 the Statistical Commission discusses regularly the work of the city groups. It reviews the accomplishments of existing groups and examines the terms of reference for proposed new groups. Based on this it encourages the existing groups to continue their work and identifies a number of critical problems around which new city groups might be formed. In order to preserve maximum flexibility city groups as a matter of principle determine their own individual mechanism of work. Still, there exist some common characteristics.
City groups are informal groups of experts primarily from national statistical agencies.
Participation by representatives is voluntary as is the existence of the group itself. If there is insufficient interest in the group then it either is not created or soon ceases to exist. Each representative is expected to fund his or her participation in the group. While each group sets its own working procedures generally a key criterion for participation is the ability of each member to contribute a substantive paper to each meeting of the group. It is usually the responsibility of the host to prepare a volume of proceedings after each meeting.