The pi-index: a new indicator for assessing scientific impact

There are several simple and sophisticated scientometric indicators generally applied in the literature (e.g. total number of publications and citations, citations per journal paper, relative citedness indexes, Hirsch index, etc.), which may characterize the publications of scientists both qualitatively and quantitatively. The calculation methods generally use data referring to the total set of papers studied. Scientific progress, however, may be attributed primarily to information in the highly cited publications. Therefore, a new indicator (π-index) is suggested for comparative assessment of scientists active in similar subject fields. The π-index is equal to one hundredth of the number of citations obtained to the top square root of the total number of journal papers (‘elite set of papers’) ranked by the decreasing number of citations. The relation of the π-index to other indexes and its dependence on the field is studied, using data of journal papers of ‘highly cited researchers’.