Thesaurus and information.

Abstract

The quantitative and semantic aspects of information contained in thesauri are discussed with regard to three types of thesaurus: a thesaurus without classification, with a hierarchical structure, and with a facet structure. The optimal structure for a thesaurus, from the quantitative point of view, will depend on the number of diagnoses, the number of subdivisions and on the frequency of the diagnoses and structures. The authors show how semantic information can be computed semi-quantitatively if the structures in a diagnosis can be designated as 'more' and 'less' important for the diagnosis in question. TDM, ICD and SNOP are compared in quantitative terms. About 70-80% of diagnoses of the circulatory system and respiratory system, but only 20% of diagnoses of the nervous system, were found to be directly transferable between TDM and ICD. With the post-co-ordinated SNOP about 80% of TDM diagnoses could be codified.