Study of Citation Distribution in Astrophysics:An Empirical Approach

Abstract

This paper has empirically established a relationship between the number of citations received by the articles (both topten cited and others) and number of articles retrieved from Web of Science database in some areas of astrophysics. The study is based on the data retrieved from Web of Science (WoS) database for the period 1990 to 2014 in some areas of astrophysics. The search terms used in WoS were selected from Thesaurus of astronomy. In all, eighteen search terms were selected from some domains of astrophysics using systematic sampling method. Four fundamental variables associated with each search term are considered for this study. These variables are: Number of retrieved documents; total citations received by all retrieved documents (including self citation); total citations received by top 10 cited documents (including self citation) and age of the retrieved documents. On the basis of these four fundamental variables, five new variables are defined as follows, i.e. Average number of citations received by all retrieved articles; average number of citations received by top ten cited articles; Citation Gain; Citation Gain Index and Citation Gain Index per unit Age or Temporary Citation Gain Index. It has been observed that citation gain is directly proportional to number of retrievals. The analysis empirically established the skewed nature of citation distribution, i.e. accumulation of more citations around highly cited articles. The Temporary Citation Gain Index showed rectangular hyperbolic pattern with Publication age.