How can differences in international university rankings be explained?

University rankings are typically presenting their results as league tables with more emphasis on final scores and positions, than on the clarification of why the universities are ranked as they are. Finding out the latter is often not possible, because final scores are based on weighted indicators where raw data and the processing of these are not publically available. In this study we use a sample of Scandinavian universities, explaining what is causing differences between them in the two most influential university rankings: Times Higher Education and the Shanghai-ranking. The results show that differences may be attributed to both small variations on what we believe are not important indicators, as well as substantial variations on what we believe are important indicators. The overall aim of this paper is to provide a methodology that can be used in understanding universities' different ranks in global university rankings.