Investigation of the external validity of the 2004 German Science Foundation author contribution calculation recommendation for medical schools’ performance-based funding systems Paul Donner* *donner@dzhw.eu ORCID: 0000-0001-5737-8483 Department 2 ‘Research System and Science Dynamics’, German Centre for Higher Education Research and Science Studies (DZHW), Germany This study examines how well an idiosyncratic authorship counting rule for co-authored publications recommended by the German Science Foundation (DFG) for medical schools and widely used in performance- based funding systems aligns with the empirical evidence. The DFG rule and two other co-author credit rules are compared with empirical data of percentage contribution statements of authors of co-authored papers in medicine. 1. Introduction For the past decades, bibliometrically informed performance-based funding systems (PBFS) have been established and became entrenched at medical schools in Germany. These systems are used to partially allocate shares of block funding from the federal states internally to subunits of a medical school. As there is no central evaluation authority, medical schools have been free to design and implement systems according to their own preferences for criteria, weights, rules, and so on, so that there is now considerable diversity of systems across schools. Practically all of them involve the counting of publications or impact factor points of publications in some way, alongside other criteria, with the intention of rewarding and encouraging internationally competitive academic research. In 2004 the Senate Commission for Clinical Research of the German Science Foundation (Deutsche Forschungsgemeinschaft, DFG), the largest and most science-politically influential research funding organization in Germany, published a recommendation for the design of PBFS at German medical schools (DFG, 2004) which would prove quite consequential. In the following years, many medical schools adjusted their systems to align with the DFG recommendations and newly established systems also often followed them. The DFG made several recommendations, including the use of 3-year running averages for calculations, distributing 20–40 % of the block funding competitively, using obtained third- party funding and publications as criteria, discouraging criteria which in their opinion do not directly reflect a unit’s own research performance (completed PhDs and habilitations, patents, offices held, book chapters, editorships, and others). Concerning publications, the recommendations criticized the exclusive use of Journal Impact Factors (p. 14) and instead promoted the development of adequate methods to judge the scientific quality of individual publications. However, it left open the back door by allowing to use Impact Factors in a ‘surrogate manner’ in the ‘intervening time’ until such methods have been developed. Furthermore, with the stated intention to prevent excessive multiple counting of the same paper by several subunits by simply including more co-authors to manipulate such a procedure, it was recommended to count first authors with a weight of one third of the Impact Factor score, last authors also with one third, and to split the remaining third among all other ‘middle’ authors (p. 15). This somewhat idiosycratic rule was not justified by any reference to published