Modeling, the essential step to consolidate and integrate a national NMDS.

How to develop a nursing minimum data set (NMDS) as a part of a nursing information system, which is itself a part of a health information system, this is the challenge presented in this paper and realized in Switzerland through the NURSING data project. The development of the CH-NMDS is not just a selection of data but a real conceptual work consisting in making the link between the information system and the terminology system and this for any level of aggregation. The building of a conceptual coherence between the collection of the data, their storage and their utilization for decision making was made by using the object modeling language, not for programming aims but statistical purposes. For example, the nursing phenomena and the nursing interventions are considered as classification concepts as well as sets of data.