THE RELEVANCE AURA OF BIBLIOGRAPHIC RECORDS

Relevance assessments of topical descriptors for bibliographic records were gathered for two dimensions: a vertical conceptual hierarchy of broad to narrow descriptors, and a horizontal linkage of related-terms spanning three descriptors. The data were analyzed for a semantic dis tance and semantic direction effect as postulated by the Semantic Dist ance Model (SDM). The vertical conceptual hierarchy exhibited a strong SDM effect. The horizontal linkages of related terms exhibited an att enuated semantic distance effect. Results showed that the horizontal s emantic distance to nonrelevance is greater for semantically narrow re cords than for semantically broad records. This difference was explain ed by introducing the construct of the stride length of conceptual sem antic steps. Horizontal semantic steps at the bottom of conceptual hie rarchies are postulated to have smaller and more uniform stride length s than horizontal semantic steps at the top of the conceptual hierarch ies. Relevance assessments in both dimensions were combined to visuali ze the relevance aura of bibliographic records. The aura for semantica lly narrow bibliographic records was found to be larger than the aura for semantically broad records. Copyright (C) 1997 Elsevier Science Lt d