Accounting for co-authorship in research evaluation: the case of experimental physics in Italy

Co-authorship practices are known to differ among distinct scientific fields, but may do so even within research communities belonging to the same field. As a consequence, standard normalisation procedures may fail and not allow a correct comparison of individual scientific performance within a given field. For instance, in recent years groups of scientists in experimental physics, particularly in the high-energy sector, have started to work within projects involving very large research groups, sometimes comprising thousands of researchers, while other scientists operating in the same general field have continued to work within more traditional, smaller scientific collaborations: as a consequence, evaluating the scientific contribution of researchers in experimental physics has become particularly difficult, even if traditional field normalisation is taken into account. The aim of this paper is to investigate the relevance of this phenomenon and discuss a method to take into account co-authorship when evaluating scientist considering the case of the Italian National scientific Habilitation program as a case study.