Co-Authorship and the Measurement of Individual Productivity

Consider a database of academic papers where each paper has a scientific worth and a group of authors. We propose a new way of measuring individual academic productivity by evaluating authorship, the extent of an author's contribution to each paper. Our method, CoScore, uses the varying levels of success of all academic partnerships to infer, simultaneously, overall individual productivity and authorship: the worth of a paper is distributed proportionally to each co-author's productivity, defined as the sum of her contributions to all papers. The CoScores of all authors are determined endogenously via the solution of a fixed point problem. We show that CoScore is well-defined and that it is uniquely characterized by three properties: consistency, invariance to merging papers, and invariance to merging scholars. We illustrate CoScore for the two thousand most cited papers in economics.