Series and Systems
Survey families or dataset series are data collection efforts that occurred over a period of time or in several geographic locations, using the same or very similar data collection methodology and instruments. Series may be multinational -- collected in more than one country -- or in a single country. Usually all the datasets in the series are collected with the support of the same institution or institutions, but individual surveys or datasets may have the support or assistance of additional parties. The advantage of series from a research perspective is that often data from a series are more easily comparable than data from a variety of sources.