Abstract
OBJECTIVES: To analyse trends in the number of authors per article over the past 10 years. DESIGN: Analysis of articles from random volumes of eight biomedical journals. SUBJECTS: Cell, Nature, Proceedings of the National Academy of Sciences USA (PNAS), Journal of Clinical Investigation (JCI), Biochemical and Biophysical Research Communications (BBRC), Journal of Clinical Oncology (JCO), New England Journal of Medicine (NEJM), Lancet. MAIN OUTCOME MEASURES: Median and modal numbers of authors. RESULTS: All journals except Cell and Nature showed a trend towards increasing authorship numbers over the study period. The trend was most noticeable in journals such as JCO which feature clinical research. General medical journals (Lancet, NEJM) with a median of six to seven authors per article published far fewer seven author than six author studies, which suggests that author number may be influenced by the Vancouver convention which precludes citation of more than six authors. CONCLUSIONS: The phenomenon of expanding authorship in biomedical journal articles is not explained by the hypothesis that newer research technologies have necessitated more extensive collaboration. Rather, the data suggest that conferral of authorship may sometimes have a volitional component which contributes to rising author numbers. It is proposed that replacement of the Vancouver convention with a "first author, last author" citation system may help stem this rise in author numbers.