Delineating complex scientific fields by an hybrid lexical-citation method: An application to nanosciences

Relevance of bibliometric indicators on scientific areas critically depends on the quality of their delineation. Macro-level studies, often based on a selected list of journals, accept a high degree of fuzziness. Micro-level studies rely on sets of individual articles in order to reduce noise and enhance precision of retrieval. The most usual information retrieval process is based on lexical queries with various levels of sophistication. In the experiment on Nanosciences reported here, this process was used as a first step, to delineate a 'seed' of literature. It has strong limitations, especially for emerging or transversal fields. In a second step, the alternative approach of citation linkages, was used to expand the bibliography starting from lexical seed. The extension process presented is ruled by three parameters, two deal with the cited side (threshold on citation score, and specificity towards the field), one with the citing side (threshold on the number of relevant references) interplaying in the 'referencing structure' function (RSF) introduced in a previous work. This type of combination proves effective for delineating the transversal field of Nanosciences. Further improvements of the method are discussed. (c) 2006 Elsevier Ltd. All rights reserved.