Descriptor and citation retrieval in the Medical Behavioral Sciences literature: Retrieval overlaps and novelty distribution

Search results for nine topics in the Medical Behavioral Sciences are reanalyzed to compare the overall performance of descriptor and citation search strategies in identifying relevant and novel documents. Overlap percentages between an aggregate "descriptor-based" database (MEDLINE, EXCERPTA MEDICA, PSYCINFO) and an aggregate "citation-based" database (SCISEARCH, SOCIAL SCISEARCH) ranged from 1% to 26%, with a median overlap of 8% relevant retrievals found using both search strategies. For seven topics in which both descriptor and citation strategies produced reasonably substantial retrievals, two patterns of search performance and novelty distribution were observed: 1) Where descriptor and citation retrieval showed little overlap, novelty retrieval percentages differed by 17-23% between the two strategies; 2) Topics with a relatively high percentage retrieval overlap showed little difference (1-4%) in descriptor and citation novelty retrieval percentages. These results reflect the varying partial congruence of two literature networks and represent two different types of subject relevance.