The relevance aura of bibliographic records

摘要

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 distance and semantic direction effect as postulated by the Semantic Distance Model (SDM). The vertical conceptual hierarchy exhibited a strong SDM effect. The horizontal linkages of related terms exhibited an attenuated semantic distance effect. Results showed that the horizontal semantic distance to nonrelevance is greater for semantically narrow records than for semantically broad records. This difference was explained by introducing the construct of the stride length of conceptual semantic steps. Horizontal semantic steps at the bottom of conceptual hierarchies are postulated to have smaller and more uniform stride lengths than horizontal semantic steps at the top of the conceptual hierarchies. Relevance assessments in both dimensions were combined to visualize the relevance aura of bibliographic records. The aura for semantically narrow bibliographic records was found to be larger than the aura for semantically broad records.