Influence of omitted citations on the bibliometric statistics of the major Manufacturing journals

Bibliometrics is a relatively young and rapidly evolving discipline. Essential for this discipline are bibliometric databases and their information content concerning scientific publications and relevant citations. Databases are unfortunately affected by errors, whose main consequence is represented by omitted citations, i.e., citations that should be ascribed to a certain (cited) paper but, for some reason, are lost. This paper studies the impact of omitted citations on the bibliometric statistics of the major Manufacturing journals. The methodology adopted is based on a recent automated algorithm-introduced in (Franceschini et al., J Am Soc Inf Sci Technol 64(10):2149-2156, 2013)-which is applied to the Web of Science (WoS) and Scopus database. Two important results of this analysis are that: (i) on average, the omitted-citation rate (p) of WoS is slightly higher than that of Scopus; and (ii) for both databases, p values do not change drastically from journal to journal and tend to slightly decrease with respect to the issue year of citing papers. Although it would seem that omitted citations do not represent a substantial problem, they may affect indicators based on citation statistics significantly. This paper analyses the effect of omitted citations on popular bibliometric indicators like the average citations per paper and its most famous variant, i.e., the ISI Impact Factor, showing that journal classifications based on these indicators may lead to questionable discriminations.